diff --git a/consensus/types/height_vote_set.go b/consensus/types/height_vote_set.go
index a155bce08..f65f365b8 100644
--- a/consensus/types/height_vote_set.go
+++ b/consensus/types/height_vote_set.go
@@ -207,6 +207,30 @@ func (hvs *HeightVoteSet) StringIndented(indent string) string {
 		indent)
 }
 
+type roundVoteBitArrays struct {
+	Round      int           `json:"round"`
+	Prevotes   *cmn.BitArray `json:"prevotes"`
+	Precommits *cmn.BitArray `json:"precommits"`
+}
+
+func (hvs *HeightVoteSet) MarshalJSON() ([]byte, error) {
+	hvs.mtx.Lock()
+	defer hvs.mtx.Unlock()
+	totalRounds := hvs.round + 1
+	roundsVotes := make([]roundVoteBitArrays, totalRounds)
+	// rounds 0 ~ hvs.round inclusive
+	for round := 0; round < totalRounds; round++ {
+		roundsVotes[round] = roundVoteBitArrays{
+			Round:      round,
+			Prevotes:   hvs.roundVoteSets[round].Prevotes.BitArray(),
+			Precommits: hvs.roundVoteSets[round].Precommits.BitArray(),
+		}
+	}
+	// TODO: all other peer catchup rounds
+
+	return cdc.MarshalJSON(roundsVotes)
+}
+
 // If a peer claims that it has 2/3 majority for given blockKey, call this.
 // NOTE: if there are too many peers, or too much peer churn,
 // this can cause memory issues.
diff --git a/types/part_set.go b/types/part_set.go
index 749943291..e4f2b9e97 100644
--- a/types/part_set.go
+++ b/types/part_set.go
@@ -264,3 +264,20 @@ func (ps *PartSet) StringShort() string {
 	defer ps.mtx.Unlock()
 	return fmt.Sprintf("(%v of %v)", ps.Count(), ps.Total())
 }
+
+func (ps *PartSet) MarshalJSON() ([]byte, error) {
+	if ps == nil {
+		return []byte("nil-PartSet"), nil
+	}
+
+	ps.mtx.Lock()
+	defer ps.mtx.Unlock()
+
+	return cdc.MarshalJSON(struct {
+		CountTotal    string        `json:"count/total"`
+		PartsBitArray *cmn.BitArray `json:"parts_bit_array"`
+	}{
+		fmt.Sprintf("%d/%d", ps.Count(), ps.Total()),
+		ps.partsBitArray.Copy(),
+	})
+}
diff --git a/types/vote_set.go b/types/vote_set.go
index e255488d6..07ef60ec6 100644
--- a/types/vote_set.go
+++ b/types/vote_set.go
@@ -445,6 +445,26 @@ func (voteSet *VoteSet) StringIndented(indent string) string {
 		indent)
 }
 
+// Marshal the VoteSet to JSON. Same as String(), just in JSON,
+// and without the height/round/type_ (since its already included in the votes).
+func (voteSet *VoteSet) MarshalJSON() ([]byte, error) {
+	voteStrings := make([]string, len(voteSet.votes))
+	for i, vote := range voteSet.votes {
+		if vote == nil {
+			voteStrings[i] = "nil-Vote"
+		} else {
+			voteStrings[i] = vote.String()
+		}
+	}
+	return cdc.MarshalJSON(struct {
+		Votes         []string          `json:"votes"`
+		VotesBitArray *cmn.BitArray     `json:"votes_bit_array"`
+		PeerMaj23s    map[P2PID]BlockID `json:"peer_maj_23s"`
+	}{
+		voteStrings, voteSet.votesBitArray, voteSet.peerMaj23s,
+	})
+}
+
 func (voteSet *VoteSet) StringShort() string {
 	if voteSet == nil {
 		return "nil-VoteSet"