diff --git a/cmd/tendermint/commands/gen_node_key.go b/cmd/tendermint/commands/gen_node_key.go
index d8b493e3c..1207c704b 100644
--- a/cmd/tendermint/commands/gen_node_key.go
+++ b/cmd/tendermint/commands/gen_node_key.go
@@ -1,11 +1,11 @@
 package commands
 
 import (
+	"encoding/json"
 	"fmt"
 
 	"github.com/spf13/cobra"
 
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	"github.com/tendermint/tendermint/types"
 )
 
@@ -20,7 +20,7 @@ var GenNodeKeyCmd = &cobra.Command{
 func genNodeKey(cmd *cobra.Command, args []string) error {
 	nodeKey := types.GenNodeKey()
 
-	bz, err := tmjson.Marshal(nodeKey)
+	bz, err := json.Marshal(nodeKey)
 	if err != nil {
 		return fmt.Errorf("nodeKey -> json: %w", err)
 	}
diff --git a/cmd/tendermint/commands/gen_validator.go b/cmd/tendermint/commands/gen_validator.go
index 830518ce9..450efad85 100644
--- a/cmd/tendermint/commands/gen_validator.go
+++ b/cmd/tendermint/commands/gen_validator.go
@@ -1,11 +1,11 @@
 package commands
 
 import (
+	"encoding/json"
 	"fmt"
 
 	"github.com/spf13/cobra"
 
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	"github.com/tendermint/tendermint/privval"
 	"github.com/tendermint/tendermint/types"
 )
@@ -29,7 +29,7 @@ func genValidator(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	jsbz, err := tmjson.Marshal(pv)
+	jsbz, err := json.Marshal(pv)
 	if err != nil {
 		return fmt.Errorf("validator -> json: %w", err)
 	}
diff --git a/cmd/tendermint/commands/show_validator.go b/cmd/tendermint/commands/show_validator.go
index b6b9c67ec..d09fce155 100644
--- a/cmd/tendermint/commands/show_validator.go
+++ b/cmd/tendermint/commands/show_validator.go
@@ -7,7 +7,7 @@ import (
 	"github.com/spf13/cobra"
 
 	"github.com/tendermint/tendermint/crypto"
-	tmjson "github.com/tendermint/tendermint/libs/json"
+	"github.com/tendermint/tendermint/internal/jsontypes"
 	tmnet "github.com/tendermint/tendermint/libs/net"
 	tmos "github.com/tendermint/tendermint/libs/os"
 	"github.com/tendermint/tendermint/privval"
@@ -70,7 +70,7 @@ func showValidator(cmd *cobra.Command, args []string) error {
 		}
 	}
 
-	bz, err := tmjson.Marshal(pubKey)
+	bz, err := jsontypes.Marshal(pubKey)
 	if err != nil {
 		return fmt.Errorf("failed to marshal private validator pubkey: %w", err)
 	}
diff --git a/config/config.go b/config/config.go
index a559e4149..3758c9241 100644
--- a/config/config.go
+++ b/config/config.go
@@ -2,6 +2,7 @@ package config
 
 import (
 	"encoding/hex"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"net/http"
@@ -9,7 +10,6 @@ import (
 	"path/filepath"
 	"time"
 
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	"github.com/tendermint/tendermint/libs/log"
 	tmos "github.com/tendermint/tendermint/libs/os"
 	"github.com/tendermint/tendermint/types"
@@ -270,7 +270,7 @@ func (cfg BaseConfig) LoadNodeKeyID() (types.NodeID, error) {
 		return "", err
 	}
 	nodeKey := types.NodeKey{}
-	err = tmjson.Unmarshal(jsonBytes, &nodeKey)
+	err = json.Unmarshal(jsonBytes, &nodeKey)
 	if err != nil {
 		return "", err
 	}
diff --git a/crypto/ed25519/ed25519.go b/crypto/ed25519/ed25519.go
index 8673ff4d5..ffd4a3ed1 100644
--- a/crypto/ed25519/ed25519.go
+++ b/crypto/ed25519/ed25519.go
@@ -13,7 +13,6 @@ import (
 	"github.com/tendermint/tendermint/crypto"
 	"github.com/tendermint/tendermint/crypto/tmhash"
 	"github.com/tendermint/tendermint/internal/jsontypes"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 )
 
 //-------------------------------------
@@ -57,9 +56,6 @@ const (
 )
 
 func init() {
-	tmjson.RegisterType(PubKey{}, PubKeyName)
-	tmjson.RegisterType(PrivKey{}, PrivKeyName)
-
 	jsontypes.MustRegister(PubKey{})
 	jsontypes.MustRegister(PrivKey{})
 }
diff --git a/crypto/secp256k1/secp256k1.go b/crypto/secp256k1/secp256k1.go
index f92b29c1f..f212874c7 100644
--- a/crypto/secp256k1/secp256k1.go
+++ b/crypto/secp256k1/secp256k1.go
@@ -11,7 +11,6 @@ import (
 	secp256k1 "github.com/btcsuite/btcd/btcec"
 	"github.com/tendermint/tendermint/crypto"
 	"github.com/tendermint/tendermint/internal/jsontypes"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 
 	// necessary for Bitcoin address format
 	"golang.org/x/crypto/ripemd160" // nolint
@@ -27,9 +26,6 @@ const (
 )
 
 func init() {
-	tmjson.RegisterType(PubKey{}, PubKeyName)
-	tmjson.RegisterType(PrivKey{}, PrivKeyName)
-
 	jsontypes.MustRegister(PubKey{})
 	jsontypes.MustRegister(PrivKey{})
 }
diff --git a/crypto/sr25519/encoding.go b/crypto/sr25519/encoding.go
index 8827ee0b1..7ff110821 100644
--- a/crypto/sr25519/encoding.go
+++ b/crypto/sr25519/encoding.go
@@ -2,7 +2,6 @@ package sr25519
 
 import (
 	"github.com/tendermint/tendermint/internal/jsontypes"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 )
 
 const (
@@ -11,9 +10,6 @@ const (
 )
 
 func init() {
-	tmjson.RegisterType(PubKey{}, PubKeyName)
-	tmjson.RegisterType(PrivKey{}, PrivKeyName)
-
 	jsontypes.MustRegister(PubKey{})
 	jsontypes.MustRegister(PrivKey{})
 }
diff --git a/internal/consensus/peer_state.go b/internal/consensus/peer_state.go
index 79f4f4430..7f3788cb4 100644
--- a/internal/consensus/peer_state.go
+++ b/internal/consensus/peer_state.go
@@ -1,6 +1,7 @@
 package consensus
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"sync"
@@ -9,7 +10,6 @@ import (
 	cstypes "github.com/tendermint/tendermint/internal/consensus/types"
 	tmsync "github.com/tendermint/tendermint/internal/libs/sync"
 	"github.com/tendermint/tendermint/libs/bits"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	"github.com/tendermint/tendermint/libs/log"
 	tmtime "github.com/tendermint/tendermint/libs/time"
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
@@ -96,8 +96,7 @@ func (ps *PeerState) GetRoundState() *cstypes.PeerRoundState {
 func (ps *PeerState) ToJSON() ([]byte, error) {
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()
-
-	return tmjson.Marshal(ps)
+	return json.Marshal(ps)
 }
 
 // GetHeight returns an atomic snapshot of the PeerRoundState's height used by
diff --git a/internal/jsontypes/jsontypes.go b/internal/jsontypes/jsontypes.go
index 16095ee2f..69405da1b 100644
--- a/internal/jsontypes/jsontypes.go
+++ b/internal/jsontypes/jsontypes.go
@@ -84,6 +84,10 @@ func Unmarshal(data []byte, v interface{}) error {
 		return fmt.Errorf("target is a nil %T", v)
 	}
 	baseType := target.Type().Elem()
+	if isNull(data) {
+		target.Elem().Set(reflect.Zero(baseType))
+		return nil
+	}
 
 	var w wrapper
 	dec := json.NewDecoder(bytes.NewReader(data))
@@ -93,7 +97,7 @@ func Unmarshal(data []byte, v interface{}) error {
 	}
 	typ, ok := registry.types[w.Type]
 	if !ok {
-		return fmt.Errorf("unknown type tag: %q", w.Type)
+		return fmt.Errorf("unknown type tag for %T: %q", v, w.Type)
 	}
 	if typ.AssignableTo(baseType) {
 		// ok: registered type is directly assignable to the target
@@ -110,3 +114,8 @@ func Unmarshal(data []byte, v interface{}) error {
 	target.Elem().Set(obj.Elem())
 	return nil
 }
+
+// isNull reports true if data is empty or is the JSON "null" value.
+func isNull(data []byte) bool {
+	return len(data) == 0 || bytes.Equal(data, []byte("null"))
+}
diff --git a/internal/rpc/core/env.go b/internal/rpc/core/env.go
index b91d73ebc..448cd85a0 100644
--- a/internal/rpc/core/env.go
+++ b/internal/rpc/core/env.go
@@ -3,6 +3,7 @@ package core
 import (
 	"context"
 	"encoding/base64"
+	"encoding/json"
 	"fmt"
 	"net"
 	"net/http"
@@ -21,7 +22,6 @@ import (
 	sm "github.com/tendermint/tendermint/internal/state"
 	"github.com/tendermint/tendermint/internal/state/indexer"
 	"github.com/tendermint/tendermint/internal/statesync"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	"github.com/tendermint/tendermint/libs/log"
 	"github.com/tendermint/tendermint/libs/strings"
 	"github.com/tendermint/tendermint/rpc/coretypes"
@@ -154,7 +154,7 @@ func (env *Environment) InitGenesisChunks() error {
 		return nil
 	}
 
-	data, err := tmjson.Marshal(env.GenDoc)
+	data, err := json.Marshal(env.GenDoc)
 	if err != nil {
 		return err
 	}
diff --git a/internal/rpc/core/evidence.go b/internal/rpc/core/evidence.go
index f85892d99..e97024b4c 100644
--- a/internal/rpc/core/evidence.go
+++ b/internal/rpc/core/evidence.go
@@ -5,25 +5,22 @@ import (
 	"fmt"
 
 	"github.com/tendermint/tendermint/rpc/coretypes"
-	"github.com/tendermint/tendermint/types"
 )
 
 // BroadcastEvidence broadcasts evidence of the misbehavior.
 // More: https://docs.tendermint.com/master/rpc/#/Evidence/broadcast_evidence
 func (env *Environment) BroadcastEvidence(
 	ctx context.Context,
-	ev types.Evidence) (*coretypes.ResultBroadcastEvidence, error) {
-
-	if ev == nil {
+	ev coretypes.Evidence,
+) (*coretypes.ResultBroadcastEvidence, error) {
+	if ev.Value == nil {
 		return nil, fmt.Errorf("%w: no evidence was provided", coretypes.ErrInvalidRequest)
 	}
-
-	if err := ev.ValidateBasic(); err != nil {
+	if err := ev.Value.ValidateBasic(); err != nil {
 		return nil, fmt.Errorf("evidence.ValidateBasic failed: %w", err)
 	}
-
-	if err := env.EvidencePool.AddEvidence(ev); err != nil {
+	if err := env.EvidencePool.AddEvidence(ev.Value); err != nil {
 		return nil, fmt.Errorf("failed to add evidence: %w", err)
 	}
-	return &coretypes.ResultBroadcastEvidence{Hash: ev.Hash()}, nil
+	return &coretypes.ResultBroadcastEvidence{Hash: ev.Value.Hash()}, nil
 }
diff --git a/internal/rpc/core/routes.go b/internal/rpc/core/routes.go
index 09be47c5c..84e8e199a 100644
--- a/internal/rpc/core/routes.go
+++ b/internal/rpc/core/routes.go
@@ -86,7 +86,7 @@ type RPCService interface {
 	BlockResults(ctx context.Context, heightPtr *int64) (*coretypes.ResultBlockResults, error)
 	BlockSearch(ctx context.Context, query string, pagePtr, perPagePtr *int, orderBy string) (*coretypes.ResultBlockSearch, error)
 	BlockchainInfo(ctx context.Context, minHeight, maxHeight int64) (*coretypes.ResultBlockchainInfo, error)
-	BroadcastEvidence(ctx context.Context, ev types.Evidence) (*coretypes.ResultBroadcastEvidence, error)
+	BroadcastEvidence(ctx context.Context, ev coretypes.Evidence) (*coretypes.ResultBroadcastEvidence, error)
 	BroadcastTxAsync(ctx context.Context, tx types.Tx) (*coretypes.ResultBroadcastTx, error)
 	BroadcastTxCommit(ctx context.Context, tx types.Tx) (*coretypes.ResultBroadcastTxCommit, error)
 	BroadcastTxSync(ctx context.Context, tx types.Tx) (*coretypes.ResultBroadcastTx, error)
diff --git a/light/proxy/routes.go b/light/proxy/routes.go
index 76cc52f73..24e7e18c2 100644
--- a/light/proxy/routes.go
+++ b/light/proxy/routes.go
@@ -38,3 +38,7 @@ func (p proxyService) Unsubscribe(ctx context.Context, query string) (*coretypes
 func (p proxyService) UnsubscribeAll(ctx context.Context) (*coretypes.ResultUnsubscribe, error) {
 	return p.UnsubscribeAllWS(ctx)
 }
+
+func (p proxyService) BroadcastEvidence(ctx context.Context, ev coretypes.Evidence) (*coretypes.ResultBroadcastEvidence, error) {
+	return p.Client.BroadcastEvidence(ctx, ev.Value)
+}
diff --git a/privval/file.go b/privval/file.go
index d5c959b9b..728e0dc67 100644
--- a/privval/file.go
+++ b/privval/file.go
@@ -18,7 +18,6 @@ import (
 	"github.com/tendermint/tendermint/internal/libs/protoio"
 	"github.com/tendermint/tendermint/internal/libs/tempfile"
 	tmbytes "github.com/tendermint/tendermint/libs/bytes"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	tmos "github.com/tendermint/tendermint/libs/os"
 	tmtime "github.com/tendermint/tendermint/libs/time"
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
@@ -49,13 +48,19 @@ func voteToStep(vote *tmproto.Vote) (int8, error) {
 
 // FilePVKey stores the immutable part of PrivValidator.
 type FilePVKey struct {
-	Address types.Address  `json:"address"`
-	PubKey  crypto.PubKey  `json:"pub_key"`
-	PrivKey crypto.PrivKey `json:"priv_key"`
+	Address types.Address
+	PubKey  crypto.PubKey
+	PrivKey crypto.PrivKey
 
 	filePath string
 }
 
+type filePVKeyJSON struct {
+	Address types.Address   `json:"address"`
+	PubKey  json.RawMessage `json:"pub_key"`
+	PrivKey json.RawMessage `json:"priv_key"`
+}
+
 func (pvKey FilePVKey) MarshalJSON() ([]byte, error) {
 	pubk, err := jsontypes.Marshal(pvKey.PubKey)
 	if err != nil {
@@ -65,11 +70,24 @@ func (pvKey FilePVKey) MarshalJSON() ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	return json.Marshal(struct {
-		Address types.Address   `json:"address"`
-		PubKey  json.RawMessage `json:"pub_key"`
-		PrivKey json.RawMessage `json:"priv_key"`
-	}{Address: pvKey.Address, PubKey: pubk, PrivKey: privk})
+	return json.Marshal(filePVKeyJSON{
+		Address: pvKey.Address, PubKey: pubk, PrivKey: privk,
+	})
+}
+
+func (pvKey *FilePVKey) UnmarshalJSON(data []byte) error {
+	var key filePVKeyJSON
+	if err := json.Unmarshal(data, &key); err != nil {
+		return err
+	}
+	if err := jsontypes.Unmarshal(key.PubKey, &pvKey.PubKey); err != nil {
+		return fmt.Errorf("decoding PubKey: %w", err)
+	}
+	if err := jsontypes.Unmarshal(key.PrivKey, &pvKey.PrivKey); err != nil {
+		return fmt.Errorf("decoding PrivKey: %w", err)
+	}
+	pvKey.Address = key.Address
+	return nil
 }
 
 // Save persists the FilePVKey to its filePath.
@@ -79,11 +97,11 @@ func (pvKey FilePVKey) Save() error {
 		return errors.New("cannot save PrivValidator key: filePath not set")
 	}
 
-	jsonBytes, err := tmjson.MarshalIndent(pvKey, "", "  ")
+	data, err := json.MarshalIndent(pvKey, "", "  ")
 	if err != nil {
 		return err
 	}
-	return tempfile.WriteFileAtomic(outFile, jsonBytes, 0600)
+	return tempfile.WriteFileAtomic(outFile, data, 0600)
 }
 
 //-------------------------------------------------------------------------------
@@ -216,7 +234,7 @@ func loadFilePV(keyFilePath, stateFilePath string, loadState bool) (*FilePV, err
 		return nil, err
 	}
 	pvKey := FilePVKey{}
-	err = tmjson.Unmarshal(keyJSONBytes, &pvKey)
+	err = json.Unmarshal(keyJSONBytes, &pvKey)
 	if err != nil {
 		return nil, fmt.Errorf("error reading PrivValidator key from %v: %w", keyFilePath, err)
 	}
diff --git a/privval/file_test.go b/privval/file_test.go
index e51b488cb..9e0c3d691 100644
--- a/privval/file_test.go
+++ b/privval/file_test.go
@@ -14,7 +14,6 @@ import (
 
 	"github.com/tendermint/tendermint/crypto/ed25519"
 	"github.com/tendermint/tendermint/crypto/tmhash"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	tmrand "github.com/tendermint/tendermint/libs/rand"
 	tmtime "github.com/tendermint/tendermint/libs/time"
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
@@ -143,7 +142,7 @@ func TestUnmarshalValidatorKey(t *testing.T) {
 }`, addr, pubB64, privB64)
 
 	val := FilePVKey{}
-	err := tmjson.Unmarshal([]byte(serialized), &val)
+	err := json.Unmarshal([]byte(serialized), &val)
 	require.NoError(t, err)
 
 	// make sure the values match
@@ -152,7 +151,7 @@ func TestUnmarshalValidatorKey(t *testing.T) {
 	assert.EqualValues(t, privKey, val.PrivKey)
 
 	// export it and make sure it is the same
-	out, err := tmjson.Marshal(val)
+	out, err := json.Marshal(val)
 	require.NoError(t, err)
 	assert.JSONEq(t, serialized, string(out))
 }
diff --git a/rpc/client/http/http.go b/rpc/client/http/http.go
index f3ae8fe1c..523253523 100644
--- a/rpc/client/http/http.go
+++ b/rpc/client/http/http.go
@@ -512,7 +512,7 @@ func (c *baseRPCClient) BroadcastEvidence(
 ) (*coretypes.ResultBroadcastEvidence, error) {
 	result := new(coretypes.ResultBroadcastEvidence)
 	if err := c.caller.Call(ctx, "broadcast_evidence", evidenceArgs{
-		Evidence: ev,
+		Evidence: coretypes.Evidence{Value: ev},
 	}, result); err != nil {
 		return nil, err
 	}
diff --git a/rpc/client/http/request.go b/rpc/client/http/request.go
index 88d6b1d1b..746cb776d 100644
--- a/rpc/client/http/request.go
+++ b/rpc/client/http/request.go
@@ -4,11 +4,8 @@ package http
 // from the client to the server.
 
 import (
-	"encoding/json"
-
-	"github.com/tendermint/tendermint/internal/jsontypes"
 	"github.com/tendermint/tendermint/libs/bytes"
-	"github.com/tendermint/tendermint/types"
+	"github.com/tendermint/tendermint/rpc/coretypes"
 )
 
 type abciQueryArgs struct {
@@ -64,17 +61,5 @@ type validatorArgs struct {
 }
 
 type evidenceArgs struct {
-	Evidence types.Evidence
-}
-
-// MarshalJSON implements json.Marshaler to encode the evidence using the
-// wrapped concrete type of the implementation.
-func (e evidenceArgs) MarshalJSON() ([]byte, error) {
-	ev, err := jsontypes.Marshal(e.Evidence)
-	if err != nil {
-		return nil, err
-	}
-	return json.Marshal(struct {
-		Evidence json.RawMessage `json:"evidence"`
-	}{Evidence: ev})
+	Evidence coretypes.Evidence `json:"evidence"`
 }
diff --git a/rpc/client/http/ws.go b/rpc/client/http/ws.go
index ceda36c3c..166a6e990 100644
--- a/rpc/client/http/ws.go
+++ b/rpc/client/http/ws.go
@@ -2,6 +2,7 @@ package http
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"strings"
@@ -9,7 +10,6 @@ import (
 	"time"
 
 	"github.com/tendermint/tendermint/internal/pubsub"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	rpcclient "github.com/tendermint/tendermint/rpc/client"
 	"github.com/tendermint/tendermint/rpc/coretypes"
 	jsonrpcclient "github.com/tendermint/tendermint/rpc/jsonrpc/client"
@@ -239,7 +239,7 @@ func (w *wsEvents) eventListener(ctx context.Context) {
 			}
 
 			result := new(coretypes.ResultEvent)
-			err := tmjson.Unmarshal(resp.Result, result)
+			err := json.Unmarshal(resp.Result, result)
 			if err != nil {
 				w.Logger.Error("failed to unmarshal response", "err", err)
 				continue
diff --git a/rpc/client/local/local.go b/rpc/client/local/local.go
index 95f3c63b9..8b2a88314 100644
--- a/rpc/client/local/local.go
+++ b/rpc/client/local/local.go
@@ -198,7 +198,7 @@ func (c *Local) BlockSearch(
 }
 
 func (c *Local) BroadcastEvidence(ctx context.Context, ev types.Evidence) (*coretypes.ResultBroadcastEvidence, error) {
-	return c.env.BroadcastEvidence(ctx, ev)
+	return c.env.BroadcastEvidence(ctx, coretypes.Evidence{Value: ev})
 }
 
 func (c *Local) Subscribe(
diff --git a/rpc/client/mock/client.go b/rpc/client/mock/client.go
index 05a3ca9cb..b47ff1e76 100644
--- a/rpc/client/mock/client.go
+++ b/rpc/client/mock/client.go
@@ -155,5 +155,5 @@ func (c Client) Validators(ctx context.Context, height *int64, page, perPage *in
 }
 
 func (c Client) BroadcastEvidence(ctx context.Context, ev types.Evidence) (*coretypes.ResultBroadcastEvidence, error) {
-	return c.env.BroadcastEvidence(ctx, ev)
+	return c.env.BroadcastEvidence(ctx, coretypes.Evidence{Value: ev})
 }
diff --git a/rpc/client/rpc_test.go b/rpc/client/rpc_test.go
index 3e0e39554..5fceaef58 100644
--- a/rpc/client/rpc_test.go
+++ b/rpc/client/rpc_test.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/base64"
+	"encoding/json"
 	"fmt"
 	"math"
 	"net/http"
@@ -21,7 +22,6 @@ import (
 	"github.com/tendermint/tendermint/crypto/encoding"
 	"github.com/tendermint/tendermint/internal/mempool"
 	rpccore "github.com/tendermint/tendermint/internal/rpc/core"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	"github.com/tendermint/tendermint/libs/log"
 	tmmath "github.com/tendermint/tendermint/libs/math"
 	"github.com/tendermint/tendermint/libs/service"
@@ -305,7 +305,7 @@ func TestClientMethodCalls(t *testing.T) {
 				doc := []byte(strings.Join(decoded, ""))
 
 				var out types.GenesisDoc
-				require.NoError(t, tmjson.Unmarshal(doc, &out),
+				require.NoError(t, json.Unmarshal(doc, &out),
 					"first: %+v, doc: %s", first, string(doc))
 			})
 			t.Run("ABCIQuery", func(t *testing.T) {
@@ -582,7 +582,7 @@ func TestClientMethodCalls(t *testing.T) {
 				})
 				t.Run("BroadcastEmpty", func(t *testing.T) {
 					_, err := c.BroadcastEvidence(ctx, nil)
-					assert.Error(t, err)
+					require.Error(t, err)
 				})
 			})
 		})
diff --git a/rpc/coretypes/responses.go b/rpc/coretypes/responses.go
index 47649557c..2a1cf45b0 100644
--- a/rpc/coretypes/responses.go
+++ b/rpc/coretypes/responses.go
@@ -3,10 +3,12 @@ package coretypes
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"time"
 
 	abci "github.com/tendermint/tendermint/abci/types"
 	"github.com/tendermint/tendermint/crypto"
+	"github.com/tendermint/tendermint/internal/jsontypes"
 	"github.com/tendermint/tendermint/libs/bytes"
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
 	"github.com/tendermint/tendermint/types"
@@ -26,7 +28,7 @@ var (
 
 // List of blocks
 type ResultBlockchainInfo struct {
-	LastHeight int64              `json:"last_height"`
+	LastHeight int64              `json:"last_height,string"`
 	BlockMetas []*types.BlockMeta `json:"block_metas"`
 }
 
@@ -40,8 +42,8 @@ type ResultGenesis struct {
 // document to JSON and then splitting the resulting payload into
 // 16 megabyte blocks and then base64 encoding each block.
 type ResultGenesisChunk struct {
-	ChunkNumber int    `json:"chunk"`
-	TotalChunks int    `json:"total"`
+	ChunkNumber int    `json:"chunk,string"`
+	TotalChunks int    `json:"total,string"`
 	Data        string `json:"data"`
 }
 
@@ -64,9 +66,9 @@ type ResultCommit struct {
 
 // ABCI results from a block
 type ResultBlockResults struct {
-	Height                int64                     `json:"height"`
+	Height                int64                     `json:"height,string"`
 	TxsResults            []*abci.ResponseDeliverTx `json:"txs_results"`
-	TotalGasUsed          int64                     `json:"total_gas_used"`
+	TotalGasUsed          int64                     `json:"total_gas_used,string"`
 	BeginBlockEvents      []abci.Event              `json:"begin_block_events"`
 	EndBlockEvents        []abci.Event              `json:"end_block_events"`
 	ValidatorUpdates      []abci.ValidatorUpdate    `json:"validator_updates"`
@@ -91,35 +93,64 @@ func NewResultCommit(header *types.Header, commit *types.Commit,
 type SyncInfo struct {
 	LatestBlockHash   bytes.HexBytes `json:"latest_block_hash"`
 	LatestAppHash     bytes.HexBytes `json:"latest_app_hash"`
-	LatestBlockHeight int64          `json:"latest_block_height"`
+	LatestBlockHeight int64          `json:"latest_block_height,string"`
 	LatestBlockTime   time.Time      `json:"latest_block_time"`
 
 	EarliestBlockHash   bytes.HexBytes `json:"earliest_block_hash"`
 	EarliestAppHash     bytes.HexBytes `json:"earliest_app_hash"`
-	EarliestBlockHeight int64          `json:"earliest_block_height"`
+	EarliestBlockHeight int64          `json:"earliest_block_height,string"`
 	EarliestBlockTime   time.Time      `json:"earliest_block_time"`
 
-	MaxPeerBlockHeight int64 `json:"max_peer_block_height"`
+	MaxPeerBlockHeight int64 `json:"max_peer_block_height,string"`
 
 	CatchingUp bool `json:"catching_up"`
 
-	TotalSyncedTime time.Duration `json:"total_synced_time"`
-	RemainingTime   time.Duration `json:"remaining_time"`
+	TotalSyncedTime time.Duration `json:"total_synced_time,string"`
+	RemainingTime   time.Duration `json:"remaining_time,string"`
 
-	TotalSnapshots      int64         `json:"total_snapshots"`
-	ChunkProcessAvgTime time.Duration `json:"chunk_process_avg_time"`
-	SnapshotHeight      int64         `json:"snapshot_height"`
-	SnapshotChunksCount int64         `json:"snapshot_chunks_count"`
-	SnapshotChunksTotal int64         `json:"snapshot_chunks_total"`
-	BackFilledBlocks    int64         `json:"backfilled_blocks"`
-	BackFillBlocksTotal int64         `json:"backfill_blocks_total"`
+	TotalSnapshots      int64         `json:"total_snapshots,string"`
+	ChunkProcessAvgTime time.Duration `json:"chunk_process_avg_time,string"`
+	SnapshotHeight      int64         `json:"snapshot_height,string"`
+	SnapshotChunksCount int64         `json:"snapshot_chunks_count,string"`
+	SnapshotChunksTotal int64         `json:"snapshot_chunks_total,string"`
+	BackFilledBlocks    int64         `json:"backfilled_blocks,string"`
+	BackFillBlocksTotal int64         `json:"backfill_blocks_total,string"`
 }
 
 // Info about the node's validator
 type ValidatorInfo struct {
-	Address     bytes.HexBytes `json:"address"`
-	PubKey      crypto.PubKey  `json:"pub_key"`
-	VotingPower int64          `json:"voting_power"`
+	Address     bytes.HexBytes
+	PubKey      crypto.PubKey
+	VotingPower int64
+}
+
+type validatorInfoJSON struct {
+	Address     bytes.HexBytes  `json:"address"`
+	PubKey      json.RawMessage `json:"pub_key"`
+	VotingPower int64           `json:"voting_power,string"`
+}
+
+func (v ValidatorInfo) MarshalJSON() ([]byte, error) {
+	pk, err := jsontypes.Marshal(v.PubKey)
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal(validatorInfoJSON{
+		Address: v.Address, PubKey: pk, VotingPower: v.VotingPower,
+	})
+}
+
+func (v *ValidatorInfo) UnmarshalJSON(data []byte) error {
+	var val validatorInfoJSON
+	if err := json.Unmarshal(data, &val); err != nil {
+		return err
+	}
+	if err := jsontypes.Unmarshal(val.PubKey, &v.PubKey); err != nil {
+		return err
+	}
+	v.Address = val.Address
+	v.VotingPower = val.VotingPower
+	return nil
 }
 
 // Node Status
@@ -142,7 +173,7 @@ func (s *ResultStatus) TxIndexEnabled() bool {
 type ResultNetInfo struct {
 	Listening bool     `json:"listening"`
 	Listeners []string `json:"listeners"`
-	NPeers    int      `json:"n_peers"`
+	NPeers    int      `json:"n_peers,string"`
 	Peers     []Peer   `json:"peers"`
 }
 
@@ -164,12 +195,11 @@ type Peer struct {
 
 // Validators for a height.
 type ResultValidators struct {
-	BlockHeight int64              `json:"block_height"`
+	BlockHeight int64              `json:"block_height,string"`
 	Validators  []*types.Validator `json:"validators"`
-	// Count of actual validators in this result
-	Count int `json:"count"`
-	// Total number of validators
-	Total int `json:"total"`
+
+	Count int `json:"count,string"` // Count of actual validators in this result
+	Total int `json:"total,string"` // Total number of validators
 }
 
 // ConsensusParams for given height
@@ -203,8 +233,7 @@ type ResultBroadcastTx struct {
 	Log          string         `json:"log"`
 	Codespace    string         `json:"codespace"`
 	MempoolError string         `json:"mempool_error"`
-
-	Hash bytes.HexBytes `json:"hash"`
+	Hash         bytes.HexBytes `json:"hash"`
 }
 
 // CheckTx and DeliverTx results
@@ -212,7 +241,7 @@ type ResultBroadcastTxCommit struct {
 	CheckTx   abci.ResponseCheckTx   `json:"check_tx"`
 	DeliverTx abci.ResponseDeliverTx `json:"deliver_tx"`
 	Hash      bytes.HexBytes         `json:"hash"`
-	Height    int64                  `json:"height"`
+	Height    int64                  `json:"height,string"`
 }
 
 // ResultCheckTx wraps abci.ResponseCheckTx.
@@ -223,7 +252,7 @@ type ResultCheckTx struct {
 // Result of querying for a tx
 type ResultTx struct {
 	Hash     bytes.HexBytes         `json:"hash"`
-	Height   int64                  `json:"height"`
+	Height   int64                  `json:"height,string"`
 	Index    uint32                 `json:"index"`
 	TxResult abci.ResponseDeliverTx `json:"tx_result"`
 	Tx       types.Tx               `json:"tx"`
@@ -233,20 +262,20 @@ type ResultTx struct {
 // Result of searching for txs
 type ResultTxSearch struct {
 	Txs        []*ResultTx `json:"txs"`
-	TotalCount int         `json:"total_count"`
+	TotalCount int         `json:"total_count,string"`
 }
 
 // ResultBlockSearch defines the RPC response type for a block search by events.
 type ResultBlockSearch struct {
 	Blocks     []*ResultBlock `json:"blocks"`
-	TotalCount int            `json:"total_count"`
+	TotalCount int            `json:"total_count,string"`
 }
 
 // List of mempool txs
 type ResultUnconfirmedTxs struct {
-	Count      int        `json:"n_txs"`
-	Total      int        `json:"total"`
-	TotalBytes int64      `json:"total_bytes"`
+	Count      int        `json:"n_txs,string"`
+	Total      int        `json:"total,string"`
+	TotalBytes int64      `json:"total_bytes,string"`
 	Txs        []types.Tx `json:"txs"`
 }
 
@@ -276,8 +305,55 @@ type (
 
 // Event data from a subscription
 type ResultEvent struct {
-	SubscriptionID string            `json:"subscription_id"`
-	Query          string            `json:"query"`
-	Data           types.TMEventData `json:"data"`
-	Events         []abci.Event      `json:"events"`
+	SubscriptionID string
+	Query          string
+	Data           types.TMEventData
+	Events         []abci.Event
 }
+
+type resultEventJSON struct {
+	SubscriptionID string          `json:"subscription_id"`
+	Query          string          `json:"query"`
+	Data           json.RawMessage `json:"data"`
+	Events         []abci.Event    `json:"events"`
+}
+
+func (r ResultEvent) MarshalJSON() ([]byte, error) {
+	data, ok := r.Data.(jsontypes.Tagged)
+	if !ok {
+		return nil, fmt.Errorf("type %T is not tagged", r.Data)
+	}
+	evt, err := jsontypes.Marshal(data)
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal(resultEventJSON{
+		SubscriptionID: r.SubscriptionID,
+		Query:          r.Query,
+		Data:           evt,
+		Events:         r.Events,
+	})
+}
+
+func (r *ResultEvent) UnmarshalJSON(data []byte) error {
+	var res resultEventJSON
+	if err := json.Unmarshal(data, &res); err != nil {
+		return err
+	}
+	if err := jsontypes.Unmarshal(res.Data, &r.Data); err != nil {
+		return err
+	}
+	r.SubscriptionID = res.SubscriptionID
+	r.Query = res.Query
+	r.Events = res.Events
+	return nil
+}
+
+// Evidence is an argument wrapper for a types.Evidence value, that handles
+// encoding and decoding through JSON.
+type Evidence struct {
+	Value types.Evidence
+}
+
+func (e Evidence) MarshalJSON() ([]byte, error)     { return jsontypes.Marshal(e.Value) }
+func (e *Evidence) UnmarshalJSON(data []byte) error { return jsontypes.Unmarshal(data, &e.Value) }
diff --git a/rpc/jsonrpc/client/decode.go b/rpc/jsonrpc/client/decode.go
index 5d41a94c0..2f5ec5fcc 100644
--- a/rpc/jsonrpc/client/decode.go
+++ b/rpc/jsonrpc/client/decode.go
@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	rpctypes "github.com/tendermint/tendermint/rpc/jsonrpc/types"
 )
 
@@ -26,7 +25,7 @@ func unmarshalResponseBytes(responseBytes []byte, expectedID rpctypes.JSONRPCInt
 	}
 
 	// Unmarshal the RawMessage into the result.
-	if err := tmjson.Unmarshal(response.Result, result); err != nil {
+	if err := json.Unmarshal(response.Result, result); err != nil {
 		return fmt.Errorf("error unmarshaling result: %w", err)
 	}
 	return nil
@@ -71,7 +70,7 @@ func unmarshalResponseBytesArray(
 	}
 
 	for i := 0; i < len(responses); i++ {
-		if err := tmjson.Unmarshal(responses[i].Result, results[i]); err != nil {
+		if err := json.Unmarshal(responses[i].Result, results[i]); err != nil {
 			return nil, fmt.Errorf("error unmarshaling #%d result: %w", i, err)
 		}
 	}
diff --git a/rpc/jsonrpc/server/http_json_handler.go b/rpc/jsonrpc/server/http_json_handler.go
index 035793d93..e41274a45 100644
--- a/rpc/jsonrpc/server/http_json_handler.go
+++ b/rpc/jsonrpc/server/http_json_handler.go
@@ -2,6 +2,7 @@ package server
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -9,8 +10,8 @@ import (
 	"net/http"
 	"reflect"
 	"sort"
+	"strconv"
 
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	"github.com/tendermint/tendermint/libs/log"
 	"github.com/tendermint/tendermint/rpc/coretypes"
 	rpctypes "github.com/tendermint/tendermint/rpc/jsonrpc/types"
@@ -63,7 +64,12 @@ func makeJSONRPCHandler(funcMap map[string]*RPCFunc, logger log.Logger) http.Han
 				continue
 			}
 
-			args, err := parseParams(rpcFunc, hreq, req)
+			req := req
+			ctx := rpctypes.WithCallInfo(hreq.Context(), &rpctypes.CallInfo{
+				RPCRequest:  &req,
+				HTTPRequest: hreq,
+			})
+			args, err := parseParams(ctx, rpcFunc, req.Params)
 			if err != nil {
 				responses = append(responses, rpctypes.RPCInvalidParamsError(
 					req.ID, fmt.Errorf("converting JSON parameters: %w", err)))
@@ -132,99 +138,101 @@ func parseRequests(data []byte) ([]rpctypes.RPCRequest, error) {
 	return reqs, nil
 }
 
-func mapParamsToArgs(
-	rpcFunc *RPCFunc,
-	params map[string]json.RawMessage,
-	argsOffset int,
-) ([]reflect.Value, error) {
+// parseParams parses the JSON parameters of rpcReq into the arguments of fn,
+// returning the corresponding argument values or an error.
+func parseParams(ctx context.Context, fn *RPCFunc, paramData []byte) ([]reflect.Value, error) {
+	params, err := parseJSONParams(fn, paramData)
+	if err != nil {
+		return nil, err
+	}
 
-	values := make([]reflect.Value, len(rpcFunc.argNames))
-	for i, argName := range rpcFunc.argNames {
-		argType := rpcFunc.args[i+argsOffset]
+	args := make([]reflect.Value, 1+len(params))
+	args[0] = reflect.ValueOf(ctx)
+	for i, param := range params {
+		ptype := fn.args[i+1]
+		if len(param) == 0 {
+			args[i+1] = reflect.Zero(ptype)
+			continue
+		}
 
-		if p, ok := params[argName]; ok && p != nil && len(p) > 0 {
-			val := reflect.New(argType)
-			err := tmjson.Unmarshal(p, val.Interface())
-			if err != nil {
-				return nil, err
+		var pval reflect.Value
+		isPtr := ptype.Kind() == reflect.Ptr
+		if isPtr {
+			pval = reflect.New(ptype.Elem())
+		} else {
+			pval = reflect.New(ptype)
+		}
+		baseType := pval.Type().Elem()
+
+		if isIntType(baseType) && isStringValue(param) {
+			var z int64String
+			if err := json.Unmarshal(param, &z); err != nil {
+				return nil, fmt.Errorf("decoding string %q: %w", fn.argNames[i], err)
 			}
-			values[i] = val.Elem()
-		} else { // use default for that type
-			values[i] = reflect.Zero(argType)
+			pval.Elem().Set(reflect.ValueOf(z).Convert(baseType))
+		} else if err := json.Unmarshal(param, pval.Interface()); err != nil {
+			return nil, fmt.Errorf("decoding %q: %w", fn.argNames[i], err)
 		}
-	}
 
-	return values, nil
+		if isPtr {
+			args[i+1] = pval
+		} else {
+			args[i+1] = pval.Elem()
+		}
+	}
+	return args, nil
 }
 
-func arrayParamsToArgs(
-	rpcFunc *RPCFunc,
-	params []json.RawMessage,
-	argsOffset int,
-) ([]reflect.Value, error) {
-
-	if len(rpcFunc.argNames) != len(params) {
-		return nil, fmt.Errorf("expected %v parameters (%v), got %v (%v)",
-			len(rpcFunc.argNames), rpcFunc.argNames, len(params), params)
-	}
+// parseJSONParams parses data and returns a slice of JSON values matching the
+// positional parameters of fn. It reports an error if data is not "null" and
+// does not encode an object or an array, or if the number of array parameters
+// does not match the argument list of fn (excluding the context).
+func parseJSONParams(fn *RPCFunc, data []byte) ([]json.RawMessage, error) {
+	base := bytes.TrimSpace(data)
+	if bytes.HasPrefix(base, []byte("{")) {
+		var m map[string]json.RawMessage
+		if err := json.Unmarshal(base, &m); err != nil {
+			return nil, fmt.Errorf("decoding parameter object: %w", err)
+		}
+		out := make([]json.RawMessage, len(fn.argNames))
+		for i, name := range fn.argNames {
+			if p, ok := m[name]; ok {
+				out[i] = p
+			}
+		}
+		return out, nil
 
-	values := make([]reflect.Value, len(params))
-	for i, p := range params {
-		argType := rpcFunc.args[i+argsOffset]
-		val := reflect.New(argType)
-		err := tmjson.Unmarshal(p, val.Interface())
-		if err != nil {
-			return nil, err
+	} else if bytes.HasPrefix(base, []byte("[")) {
+		var m []json.RawMessage
+		if err := json.Unmarshal(base, &m); err != nil {
+			return nil, fmt.Errorf("decoding parameter array: %w", err)
 		}
-		values[i] = val.Elem()
+		if len(m) != len(fn.argNames) {
+			return nil, fmt.Errorf("got %d parameters, want %d", len(m), len(fn.argNames))
+		}
+		return m, nil
+
+	} else if bytes.Equal(base, []byte("null")) {
+		return make([]json.RawMessage, len(fn.argNames)), nil
 	}
-	return values, nil
+
+	return nil, errors.New("parameters must be an object or an array")
 }
 
-// parseParams parses the JSON parameters of rpcReq into the arguments of fn,
-// returning the corresponding argument values or an error.
-func parseParams(fn *RPCFunc, httpReq *http.Request, rpcReq rpctypes.RPCRequest) ([]reflect.Value, error) {
-	ctx := rpctypes.WithCallInfo(httpReq.Context(), &rpctypes.CallInfo{
-		RPCRequest:  &rpcReq,
-		HTTPRequest: httpReq,
-	})
-	args := []reflect.Value{reflect.ValueOf(ctx)}
-	if len(rpcReq.Params) == 0 {
-		return args, nil
-	}
-	fargs, err := jsonParamsToArgs(fn, rpcReq.Params)
-	if err != nil {
-		return nil, err
-	}
-	return append(args, fargs...), nil
+// isStringValue reports whether data is a JSON string value.
+func isStringValue(data json.RawMessage) bool {
+	return len(data) != 0 && data[0] == '"'
 }
 
-// raw is unparsed json (from json.RawMessage) encoding either a map or an
-// array.
-//
-// Example:
-//   rpcFunc.args = [context.Context string]
-//   rpcFunc.argNames = ["arg"]
-func jsonParamsToArgs(rpcFunc *RPCFunc, raw []byte) ([]reflect.Value, error) {
-	const argsOffset = 1
-
-	// TODO: Make more efficient, perhaps by checking the first character for '{' or '['?
-	// First, try to get the map.
-	var m map[string]json.RawMessage
-	err := json.Unmarshal(raw, &m)
-	if err == nil {
-		return mapParamsToArgs(rpcFunc, m, argsOffset)
-	}
+type int64String int64
 
-	// Otherwise, try an array.
-	var a []json.RawMessage
-	err = json.Unmarshal(raw, &a)
-	if err == nil {
-		return arrayParamsToArgs(rpcFunc, a, argsOffset)
+func (z *int64String) UnmarshalText(data []byte) error {
+	v, err := strconv.ParseInt(string(data), 10, 64)
+	if err != nil {
+		return err
 	}
-
-	// Otherwise, bad format, we cannot parse
-	return nil, fmt.Errorf("unknown type for JSON params: %v. Expected map or array", err)
+	*z = int64String(v)
+	return nil
 }
 
 // writes a list of available rpc endpoints as an html page
diff --git a/rpc/jsonrpc/server/http_json_handler_test.go b/rpc/jsonrpc/server/http_json_handler_test.go
index 15aa8c4c1..2d56ef072 100644
--- a/rpc/jsonrpc/server/http_json_handler_test.go
+++ b/rpc/jsonrpc/server/http_json_handler_test.go
@@ -46,7 +46,7 @@ func TestRPCParams(t *testing.T) {
 		// id not captured in JSON parsing failures
 		{`{"method": "c", "id": "0", "params": a}`, "invalid character", nil},
 		{`{"method": "c", "id": "0", "params": ["a"]}`, "got 1", rpctypes.JSONRPCStringID("0")},
-		{`{"method": "c", "id": "0", "params": ["a", "b"]}`, "invalid character", rpctypes.JSONRPCStringID("0")},
+		{`{"method": "c", "id": "0", "params": ["a", "b"]}`, "invalid syntax", rpctypes.JSONRPCStringID("0")},
 		{`{"method": "c", "id": "0", "params": [1, 1]}`, "of type string", rpctypes.JSONRPCStringID("0")},
 
 		// no ID - notification
diff --git a/rpc/jsonrpc/server/parse_test.go b/rpc/jsonrpc/server/parse_test.go
index 9b222b507..ee0ab5d79 100644
--- a/rpc/jsonrpc/server/parse_test.go
+++ b/rpc/jsonrpc/server/parse_test.go
@@ -153,17 +153,17 @@ func TestParseJSONRPC(t *testing.T) {
 		{`[7,"flew",100]`, 0, "", true},
 		{`{"name": -12, "height": "fred"}`, 0, "", true},
 	}
+	ctx := context.Background()
 	for idx, tc := range cases {
 		i := strconv.Itoa(idx)
-		data := []byte(tc.raw)
-		vals, err := jsonParamsToArgs(call, data)
+		vals, err := parseParams(ctx, call, []byte(tc.raw))
 		if tc.fail {
 			assert.Error(t, err, i)
 		} else {
 			assert.NoError(t, err, "%s: %+v", i, err)
-			if assert.Equal(t, 2, len(vals), i) {
-				assert.Equal(t, tc.height, vals[0].Int(), i)
-				assert.Equal(t, tc.name, vals[1].String(), i)
+			if assert.Equal(t, 3, len(vals), i) { // ctx, height, name
+				assert.Equal(t, tc.height, vals[1].Int(), i)
+				assert.Equal(t, tc.name, vals[2].String(), i)
 			}
 		}
 
diff --git a/rpc/jsonrpc/server/ws_handler.go b/rpc/jsonrpc/server/ws_handler.go
index 818e66512..d3051903d 100644
--- a/rpc/jsonrpc/server/ws_handler.go
+++ b/rpc/jsonrpc/server/ws_handler.go
@@ -6,7 +6,6 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
-	"reflect"
 	"runtime/debug"
 	"time"
 
@@ -371,18 +370,14 @@ func (wsc *wsConnection) readRoutine(ctx context.Context) {
 				RPCRequest: &request,
 				WSConn:     wsc,
 			})
-			args := []reflect.Value{reflect.ValueOf(fctx)}
-			if len(request.Params) > 0 {
-				fnArgs, err := jsonParamsToArgs(rpcFunc, request.Params)
-				if err != nil {
-					if err := wsc.WriteRPCResponse(writeCtx,
-						rpctypes.RPCInvalidParamsError(request.ID, fmt.Errorf("error converting json params to arguments: %w", err)),
-					); err != nil {
-						wsc.Logger.Error("error writing RPC response", "err", err)
-					}
-					continue
+			args, err := parseParams(fctx, rpcFunc, request.Params)
+			if err != nil {
+				if err := wsc.WriteRPCResponse(writeCtx, rpctypes.RPCInvalidParamsError(
+					request.ID, fmt.Errorf("error converting json params to arguments: %w", err)),
+				); err != nil {
+					wsc.Logger.Error("error writing RPC response", "err", err)
 				}
-				args = append(args, fnArgs...)
+				continue
 			}
 
 			returns := rpcFunc.f.Call(args)
diff --git a/rpc/jsonrpc/types/types.go b/rpc/jsonrpc/types/types.go
index d13c2b842..108d056a7 100644
--- a/rpc/jsonrpc/types/types.go
+++ b/rpc/jsonrpc/types/types.go
@@ -7,8 +7,6 @@ import (
 	"net/http"
 	"reflect"
 	"strings"
-
-	tmjson "github.com/tendermint/tendermint/libs/json"
 )
 
 // a wrapper to emulate a sum type: jsonrpcid = string | int
@@ -100,29 +98,10 @@ func (req RPCRequest) String() string {
 
 // ParamsToRequest constructs a new RPCRequest with the given ID, method, and parameters.
 func ParamsToRequest(id jsonrpcid, method string, params interface{}) (RPCRequest, error) {
-	var payload json.RawMessage
-	var err error
-	switch t := params.(type) {
-	case map[string]interface{}:
-		// TODO(creachadair): This special case preserves existing behavior that
-		// relies on the custom JSON encoding library. Remove it once that
-		// requirement has been removed.
-		paramsMap := make(map[string]json.RawMessage, len(t))
-		for name, value := range t {
-			valueJSON, err := tmjson.Marshal(value)
-			if err != nil {
-				return RPCRequest{}, err
-			}
-			paramsMap[name] = valueJSON
-		}
-		payload, err = json.Marshal(paramsMap)
-	default:
-		payload, err = json.Marshal(params)
-	}
+	payload, err := json.Marshal(params)
 	if err != nil {
 		return RPCRequest{}, err
 	}
-
 	return NewRPCRequest(id, method, payload), nil
 }
 
@@ -162,6 +141,7 @@ func (resp *RPCResponse) UnmarshalJSON(data []byte) error {
 	if err != nil {
 		return err
 	}
+
 	resp.JSONRPC = unsafeResp.JSONRPC
 	resp.Error = unsafeResp.Error
 	resp.Result = unsafeResp.Result
@@ -177,18 +157,11 @@ func (resp *RPCResponse) UnmarshalJSON(data []byte) error {
 }
 
 func NewRPCSuccessResponse(id jsonrpcid, res interface{}) RPCResponse {
-	var rawMsg json.RawMessage
-
-	if res != nil {
-		var js []byte
-		js, err := tmjson.Marshal(res)
-		if err != nil {
-			return RPCInternalError(id, fmt.Errorf("error marshaling response: %w", err))
-		}
-		rawMsg = json.RawMessage(js)
+	result, err := json.Marshal(res)
+	if err != nil {
+		return RPCInternalError(id, fmt.Errorf("error marshaling response: %w", err))
 	}
-
-	return RPCResponse{JSONRPC: "2.0", ID: id, Result: rawMsg}
+	return RPCResponse{JSONRPC: "2.0", ID: id, Result: result}
 }
 
 func NewRPCErrorResponse(id jsonrpcid, code int, msg string, data string) RPCResponse {
diff --git a/test/e2e/runner/evidence.go b/test/e2e/runner/evidence.go
index a81094ad7..8f8408ff1 100644
--- a/test/e2e/runner/evidence.go
+++ b/test/e2e/runner/evidence.go
@@ -3,6 +3,7 @@ package main
 import (
 	"bytes"
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"math/rand"
@@ -13,7 +14,6 @@ import (
 	"github.com/tendermint/tendermint/crypto"
 	"github.com/tendermint/tendermint/crypto/tmhash"
 	"github.com/tendermint/tendermint/internal/test/factory"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	"github.com/tendermint/tendermint/privval"
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
 	e2e "github.com/tendermint/tendermint/test/e2e/pkg"
@@ -241,7 +241,7 @@ func readPrivKey(keyFilePath string) (crypto.PrivKey, error) {
 		return nil, err
 	}
 	pvKey := privval.FilePVKey{}
-	err = tmjson.Unmarshal(keyJSONBytes, &pvKey)
+	err = json.Unmarshal(keyJSONBytes, &pvKey)
 	if err != nil {
 		return nil, fmt.Errorf("error reading PrivValidator key from %v: %w", keyFilePath, err)
 	}
diff --git a/types/events.go b/types/events.go
index 00bed4b60..7a4d7d543 100644
--- a/types/events.go
+++ b/types/events.go
@@ -6,9 +6,9 @@ import (
 	"strings"
 
 	abci "github.com/tendermint/tendermint/abci/types"
+	"github.com/tendermint/tendermint/internal/jsontypes"
 	tmpubsub "github.com/tendermint/tendermint/internal/pubsub"
 	tmquery "github.com/tendermint/tendermint/internal/pubsub/query"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 )
 
 // Reserved event types (alphabetically sorted).
@@ -90,23 +90,21 @@ var (
 // ENCODING / DECODING
 
 // TMEventData implements events.EventData.
-type TMEventData interface {
-	// empty interface
-}
+type TMEventData interface{}
 
 func init() {
-	tmjson.RegisterType(EventDataNewBlock{}, "tendermint/event/NewBlock")
-	tmjson.RegisterType(EventDataNewBlockHeader{}, "tendermint/event/NewBlockHeader")
-	tmjson.RegisterType(EventDataNewEvidence{}, "tendermint/event/NewEvidence")
-	tmjson.RegisterType(EventDataTx{}, "tendermint/event/Tx")
-	tmjson.RegisterType(EventDataRoundState{}, "tendermint/event/RoundState")
-	tmjson.RegisterType(EventDataNewRound{}, "tendermint/event/NewRound")
-	tmjson.RegisterType(EventDataCompleteProposal{}, "tendermint/event/CompleteProposal")
-	tmjson.RegisterType(EventDataVote{}, "tendermint/event/Vote")
-	tmjson.RegisterType(EventDataValidatorSetUpdates{}, "tendermint/event/ValidatorSetUpdates")
-	tmjson.RegisterType(EventDataString(""), "tendermint/event/ProposalString")
-	tmjson.RegisterType(EventDataBlockSyncStatus{}, "tendermint/event/FastSyncStatus")
-	tmjson.RegisterType(EventDataStateSyncStatus{}, "tendermint/event/StateSyncStatus")
+	jsontypes.MustRegister(EventDataBlockSyncStatus{})
+	jsontypes.MustRegister(EventDataCompleteProposal{})
+	jsontypes.MustRegister(EventDataNewBlock{})
+	jsontypes.MustRegister(EventDataNewBlockHeader{})
+	jsontypes.MustRegister(EventDataNewEvidence{})
+	jsontypes.MustRegister(EventDataNewRound{})
+	jsontypes.MustRegister(EventDataRoundState{})
+	jsontypes.MustRegister(EventDataStateSyncStatus{})
+	jsontypes.MustRegister(EventDataTx{})
+	jsontypes.MustRegister(EventDataValidatorSetUpdates{})
+	jsontypes.MustRegister(EventDataVote{})
+	jsontypes.MustRegister(EventDataString(""))
 }
 
 // Most event messages are basic types (a block, a transaction)
@@ -120,6 +118,9 @@ type EventDataNewBlock struct {
 	ResultEndBlock   abci.ResponseEndBlock   `json:"result_end_block"`
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataNewBlock) TypeTag() string { return "tendermint/event/NewBlock" }
+
 type EventDataNewBlockHeader struct {
 	Header Header `json:"header"`
 
@@ -128,17 +129,26 @@ type EventDataNewBlockHeader struct {
 	ResultEndBlock   abci.ResponseEndBlock   `json:"result_end_block"`
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataNewBlockHeader) TypeTag() string { return "tendermint/event/NewBlockHeader" }
+
 type EventDataNewEvidence struct {
 	Evidence Evidence `json:"evidence"`
 
 	Height int64 `json:"height"`
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataNewEvidence) TypeTag() string { return "tendermint/event/NewEvidence" }
+
 // All txs fire EventDataTx
 type EventDataTx struct {
 	abci.TxResult
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataTx) TypeTag() string { return "tendermint/event/Tx" }
+
 // NOTE: This goes into the replay WAL
 type EventDataRoundState struct {
 	Height int64  `json:"height"`
@@ -146,6 +156,9 @@ type EventDataRoundState struct {
 	Step   string `json:"step"`
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataRoundState) TypeTag() string { return "tendermint/event/RoundState" }
+
 type ValidatorInfo struct {
 	Address Address `json:"address"`
 	Index   int32   `json:"index"`
@@ -159,6 +172,9 @@ type EventDataNewRound struct {
 	Proposer ValidatorInfo `json:"proposer"`
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataNewRound) TypeTag() string { return "tendermint/event/NewRound" }
+
 type EventDataCompleteProposal struct {
 	Height int64  `json:"height"`
 	Round  int32  `json:"round"`
@@ -167,16 +183,28 @@ type EventDataCompleteProposal struct {
 	BlockID BlockID `json:"block_id"`
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataCompleteProposal) TypeTag() string { return "tendermint/event/CompleteProposal" }
+
 type EventDataVote struct {
 	Vote *Vote
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataVote) TypeTag() string { return "tendermint/event/Vote" }
+
 type EventDataString string
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataString) TypeTag() string { return "tendermint/event/ProposalString" }
+
 type EventDataValidatorSetUpdates struct {
 	ValidatorUpdates []*Validator `json:"validator_updates"`
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataValidatorSetUpdates) TypeTag() string { return "tendermint/event/ValidatorSetUpdates" }
+
 // EventDataBlockSyncStatus shows the fastsync status and the
 // height when the node state sync mechanism changes.
 type EventDataBlockSyncStatus struct {
@@ -184,6 +212,9 @@ type EventDataBlockSyncStatus struct {
 	Height   int64 `json:"height"`
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataBlockSyncStatus) TypeTag() string { return "tendermint/event/FastSyncStatus" }
+
 // EventDataStateSyncStatus shows the statesync status and the
 // height when the node state sync mechanism changes.
 type EventDataStateSyncStatus struct {
@@ -191,6 +222,9 @@ type EventDataStateSyncStatus struct {
 	Height   int64 `json:"height"`
 }
 
+// TypeTag implements the required method of jsontypes.Tagged.
+func (EventDataStateSyncStatus) TypeTag() string { return "tendermint/event/StateSyncStatus" }
+
 // PUBSUB
 
 const (
diff --git a/types/evidence.go b/types/evidence.go
index cca6fc899..c9a60786a 100644
--- a/types/evidence.go
+++ b/types/evidence.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/binary"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"sort"
@@ -14,7 +15,6 @@ import (
 	"github.com/tendermint/tendermint/crypto/merkle"
 	"github.com/tendermint/tendermint/crypto/tmhash"
 	"github.com/tendermint/tendermint/internal/jsontypes"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	tmrand "github.com/tendermint/tendermint/libs/rand"
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
 )
@@ -554,6 +554,33 @@ func LightClientAttackEvidenceFromProto(lpb *tmproto.LightClientAttackEvidence)
 // EvidenceList is a list of Evidence. Evidences is not a word.
 type EvidenceList []Evidence
 
+func (evl EvidenceList) MarshalJSON() ([]byte, error) {
+	lst := make([]json.RawMessage, len(evl))
+	for i, ev := range evl {
+		bits, err := jsontypes.Marshal(ev)
+		if err != nil {
+			return nil, err
+		}
+		lst[i] = bits
+	}
+	return json.Marshal(lst)
+}
+
+func (evl *EvidenceList) UnmarshalJSON(data []byte) error {
+	var lst []json.RawMessage
+	if err := json.Unmarshal(data, &lst); err != nil {
+		return err
+	}
+	out := make([]Evidence, len(lst))
+	for i, elt := range lst {
+		if err := jsontypes.Unmarshal(elt, &out[i]); err != nil {
+			return err
+		}
+	}
+	*evl = EvidenceList(out)
+	return nil
+}
+
 // Hash returns the simple merkle root hash of the EvidenceList.
 func (evl EvidenceList) Hash() []byte {
 	// These allocations are required because Evidence is not of type Bytes, and
@@ -638,9 +665,6 @@ func EvidenceFromProto(evidence *tmproto.Evidence) (Evidence, error) {
 }
 
 func init() {
-	tmjson.RegisterType(&DuplicateVoteEvidence{}, "tendermint/DuplicateVoteEvidence")
-	tmjson.RegisterType(&LightClientAttackEvidence{}, "tendermint/LightClientAttackEvidence")
-
 	jsontypes.MustRegister((*DuplicateVoteEvidence)(nil))
 	jsontypes.MustRegister((*LightClientAttackEvidence)(nil))
 }
diff --git a/types/genesis.go b/types/genesis.go
index d89de6ea2..f711a7090 100644
--- a/types/genesis.go
+++ b/types/genesis.go
@@ -11,7 +11,6 @@ import (
 	"github.com/tendermint/tendermint/crypto"
 	"github.com/tendermint/tendermint/internal/jsontypes"
 	tmbytes "github.com/tendermint/tendermint/libs/bytes"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	tmtime "github.com/tendermint/tendermint/libs/time"
 )
 
@@ -28,10 +27,17 @@ const (
 
 // GenesisValidator is an initial validator.
 type GenesisValidator struct {
-	Address Address       `json:"address"`
-	PubKey  crypto.PubKey `json:"pub_key"`
-	Power   int64         `json:"power,string"`
-	Name    string        `json:"name"`
+	Address Address
+	PubKey  crypto.PubKey
+	Power   int64
+	Name    string
+}
+
+type genesisValidatorJSON struct {
+	Address Address         `json:"address"`
+	PubKey  json.RawMessage `json:"pub_key"`
+	Power   int64           `json:"power,string"`
+	Name    string          `json:"name"`
 }
 
 func (g GenesisValidator) MarshalJSON() ([]byte, error) {
@@ -39,19 +45,30 @@ func (g GenesisValidator) MarshalJSON() ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	return json.Marshal(struct {
-		Address Address         `json:"address"`
-		PubKey  json.RawMessage `json:"pub_key"`
-		Power   int64           `json:"power,string"`
-		Name    string          `json:"name"`
-	}{Address: g.Address, PubKey: pk, Power: g.Power, Name: g.Name})
+	return json.Marshal(genesisValidatorJSON{
+		Address: g.Address, PubKey: pk, Power: g.Power, Name: g.Name,
+	})
+}
+
+func (g *GenesisValidator) UnmarshalJSON(data []byte) error {
+	var gv genesisValidatorJSON
+	if err := json.Unmarshal(data, &gv); err != nil {
+		return err
+	}
+	if err := jsontypes.Unmarshal(gv.PubKey, &g.PubKey); err != nil {
+		return err
+	}
+	g.Address = gv.Address
+	g.Power = gv.Power
+	g.Name = gv.Name
+	return nil
 }
 
 // GenesisDoc defines the initial conditions for a tendermint blockchain, in particular its validator set.
 type GenesisDoc struct {
 	GenesisTime     time.Time          `json:"genesis_time"`
 	ChainID         string             `json:"chain_id"`
-	InitialHeight   int64              `json:"initial_height"`
+	InitialHeight   int64              `json:"initial_height,string"`
 	ConsensusParams *ConsensusParams   `json:"consensus_params,omitempty"`
 	Validators      []GenesisValidator `json:"validators,omitempty"`
 	AppHash         tmbytes.HexBytes   `json:"app_hash"`
@@ -60,7 +77,7 @@ type GenesisDoc struct {
 
 // SaveAs is a utility method for saving GenensisDoc as a JSON file.
 func (genDoc *GenesisDoc) SaveAs(file string) error {
-	genDocBytes, err := tmjson.MarshalIndent(genDoc, "", "  ")
+	genDocBytes, err := json.MarshalIndent(genDoc, "", "  ")
 	if err != nil {
 		return err
 	}
@@ -125,7 +142,7 @@ func (genDoc *GenesisDoc) ValidateAndComplete() error {
 // GenesisDocFromJSON unmarshalls JSON data into a GenesisDoc.
 func GenesisDocFromJSON(jsonBlob []byte) (*GenesisDoc, error) {
 	genDoc := GenesisDoc{}
-	err := tmjson.Unmarshal(jsonBlob, &genDoc)
+	err := json.Unmarshal(jsonBlob, &genDoc)
 	if err != nil {
 		return nil, err
 	}
diff --git a/types/genesis_test.go b/types/genesis_test.go
index 422c2125f..a82ce46ea 100644
--- a/types/genesis_test.go
+++ b/types/genesis_test.go
@@ -1,6 +1,7 @@
 package types
 
 import (
+	"encoding/json"
 	"os"
 	"testing"
 
@@ -8,7 +9,6 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/tendermint/tendermint/crypto/ed25519"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	tmtime "github.com/tendermint/tendermint/libs/time"
 )
 
@@ -82,7 +82,7 @@ func TestGenesisGood(t *testing.T) {
 		ChainID:    "abc",
 		Validators: []GenesisValidator{{pubkey.Address(), pubkey, 10, "myval"}},
 	}
-	genDocBytes, err = tmjson.Marshal(baseGenDoc)
+	genDocBytes, err = json.Marshal(baseGenDoc)
 	assert.NoError(t, err, "error marshaling genDoc")
 
 	// test base gendoc and check consensus params were filled
@@ -94,14 +94,14 @@ func TestGenesisGood(t *testing.T) {
 	assert.NotNil(t, genDoc.Validators[0].Address, "expected validator's address to be filled in")
 
 	// create json with consensus params filled
-	genDocBytes, err = tmjson.Marshal(genDoc)
+	genDocBytes, err = json.Marshal(genDoc)
 	assert.NoError(t, err, "error marshaling genDoc")
 	genDoc, err = GenesisDocFromJSON(genDocBytes)
 	assert.NoError(t, err, "expected no error for valid genDoc json")
 
 	// test with invalid consensus params
 	genDoc.ConsensusParams.Block.MaxBytes = 0
-	genDocBytes, err = tmjson.Marshal(genDoc)
+	genDocBytes, err = json.Marshal(genDoc)
 	assert.NoError(t, err, "error marshaling genDoc")
 	_, err = GenesisDocFromJSON(genDocBytes)
 	assert.Error(t, err, "expected error for genDoc json with block size of 0")
diff --git a/types/node_info.go b/types/node_info.go
index 902ca759b..57aced054 100644
--- a/types/node_info.go
+++ b/types/node_info.go
@@ -24,9 +24,9 @@ func MaxNodeInfoSize() int {
 
 // ProtocolVersion contains the protocol versions for the software.
 type ProtocolVersion struct {
-	P2P   uint64 `json:"p2p"`
-	Block uint64 `json:"block"`
-	App   uint64 `json:"app"`
+	P2P   uint64 `json:"p2p,string"`
+	Block uint64 `json:"block,string"`
+	App   uint64 `json:"app,string"`
 }
 
 //-------------------------------------------------------------
diff --git a/types/node_key.go b/types/node_key.go
index 8f59b6085..927e17065 100644
--- a/types/node_key.go
+++ b/types/node_key.go
@@ -7,7 +7,6 @@ import (
 	"github.com/tendermint/tendermint/crypto"
 	"github.com/tendermint/tendermint/crypto/ed25519"
 	"github.com/tendermint/tendermint/internal/jsontypes"
-	tmjson "github.com/tendermint/tendermint/libs/json"
 	tmos "github.com/tendermint/tendermint/libs/os"
 )
 
@@ -19,9 +18,14 @@ import (
 // It contains the nodes private key for authentication.
 type NodeKey struct {
 	// Canonical ID - hex-encoded pubkey's address (IDByteLength bytes)
-	ID NodeID `json:"id"`
+	ID NodeID
 	// Private key
-	PrivKey crypto.PrivKey `json:"priv_key"`
+	PrivKey crypto.PrivKey
+}
+
+type nodeKeyJSON struct {
+	ID      NodeID          `json:"id"`
+	PrivKey json.RawMessage `json:"priv_key"`
 }
 
 func (nk NodeKey) MarshalJSON() ([]byte, error) {
@@ -29,10 +33,22 @@ func (nk NodeKey) MarshalJSON() ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	return json.Marshal(struct {
-		ID      NodeID          `json:"id"`
-		PrivKey json.RawMessage `json:"priv_key"`
-	}{ID: nk.ID, PrivKey: pk})
+	return json.Marshal(nodeKeyJSON{
+		ID: nk.ID, PrivKey: pk,
+	})
+}
+
+func (nk *NodeKey) UnmarshalJSON(data []byte) error {
+	var nkjson nodeKeyJSON
+	if err := json.Unmarshal(data, &nkjson); err != nil {
+		return err
+	}
+	var pk crypto.PrivKey
+	if err := jsontypes.Unmarshal(nkjson.PrivKey, &pk); err != nil {
+		return err
+	}
+	*nk = NodeKey{ID: nkjson.ID, PrivKey: pk}
+	return nil
 }
 
 // PubKey returns the peer's PubKey
@@ -42,7 +58,7 @@ func (nk NodeKey) PubKey() crypto.PubKey {
 
 // SaveAs persists the NodeKey to filePath.
 func (nk NodeKey) SaveAs(filePath string) error {
-	jsonBytes, err := tmjson.Marshal(nk)
+	jsonBytes, err := json.Marshal(nk)
 	if err != nil {
 		return err
 	}
@@ -85,7 +101,7 @@ func LoadNodeKey(filePath string) (NodeKey, error) {
 		return NodeKey{}, err
 	}
 	nodeKey := NodeKey{}
-	err = tmjson.Unmarshal(jsonBytes, &nodeKey)
+	err = json.Unmarshal(jsonBytes, &nodeKey)
 	if err != nil {
 		return NodeKey{}, err
 	}
diff --git a/types/params.go b/types/params.go
index 32d0f71c8..5ba065edf 100644
--- a/types/params.go
+++ b/types/params.go
@@ -54,15 +54,15 @@ type HashedParams struct {
 // BlockParams define limits on the block size and gas plus minimum time
 // between blocks.
 type BlockParams struct {
-	MaxBytes int64 `json:"max_bytes"`
-	MaxGas   int64 `json:"max_gas"`
+	MaxBytes int64 `json:"max_bytes,string"`
+	MaxGas   int64 `json:"max_gas,string"`
 }
 
 // EvidenceParams determine how we handle evidence of malfeasance.
 type EvidenceParams struct {
-	MaxAgeNumBlocks int64         `json:"max_age_num_blocks"` // only accept new evidence more recent than this
-	MaxAgeDuration  time.Duration `json:"max_age_duration"`
-	MaxBytes        int64         `json:"max_bytes"`
+	MaxAgeNumBlocks int64         `json:"max_age_num_blocks,string"` // only accept new evidence more recent than this
+	MaxAgeDuration  time.Duration `json:"max_age_duration,string"`
+	MaxBytes        int64         `json:"max_bytes,string"`
 }
 
 // ValidatorParams restrict the public key types validators can use.
@@ -72,7 +72,7 @@ type ValidatorParams struct {
 }
 
 type VersionParams struct {
-	AppVersion uint64 `json:"app_version"`
+	AppVersion uint64 `json:"app_version,string"`
 }
 
 // DefaultConsensusParams returns a default ConsensusParams.
diff --git a/types/validator.go b/types/validator.go
index 9d48c93e7..7504e2125 100644
--- a/types/validator.go
+++ b/types/validator.go
@@ -17,23 +17,47 @@ import (
 // NOTE: The ProposerPriority is not included in Validator.Hash();
 // make sure to update that method if changes are made here
 type Validator struct {
-	Address          Address       `json:"address"`
-	PubKey           crypto.PubKey `json:"pub_key"`
-	VotingPower      int64         `json:"voting_power,string"`
-	ProposerPriority int64         `json:"proposer_priority,string"`
+	Address          Address
+	PubKey           crypto.PubKey
+	VotingPower      int64
+	ProposerPriority int64
+}
+
+type validatorJSON struct {
+	Address          Address         `json:"address"`
+	PubKey           json.RawMessage `json:"pub_key,omitempty"`
+	VotingPower      int64           `json:"voting_power,string"`
+	ProposerPriority int64           `json:"proposer_priority,string"`
 }
 
 func (v Validator) MarshalJSON() ([]byte, error) {
-	pk, err := jsontypes.Marshal(v.PubKey)
-	if err != nil {
-		return nil, err
+	val := validatorJSON{
+		Address:          v.Address,
+		VotingPower:      v.VotingPower,
+		ProposerPriority: v.ProposerPriority,
 	}
-	return json.Marshal(struct {
-		Addr     Address         `json:"address"`
-		PubKey   json.RawMessage `json:"pub_key"`
-		Power    int64           `json:"voting_power,string"`
-		Priority int64           `json:"proposer_priority,string"`
-	}{Addr: v.Address, PubKey: pk, Power: v.VotingPower, Priority: v.ProposerPriority})
+	if v.PubKey != nil {
+		pk, err := jsontypes.Marshal(v.PubKey)
+		if err != nil {
+			return nil, err
+		}
+		val.PubKey = pk
+	}
+	return json.Marshal(val)
+}
+
+func (v *Validator) UnmarshalJSON(data []byte) error {
+	var val validatorJSON
+	if err := json.Unmarshal(data, &val); err != nil {
+		return err
+	}
+	if err := jsontypes.Unmarshal(val.PubKey, &v.PubKey); err != nil {
+		return err
+	}
+	v.Address = val.Address
+	v.VotingPower = val.VotingPower
+	v.ProposerPriority = val.ProposerPriority
+	return nil
 }
 
 // NewValidator returns a new validator with the given pubkey and voting power.