diff --git a/Cargo.lock b/Cargo.lock
index 4cfb518e..2373df3e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -69,6 +69,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "base64"
+version = "0.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d5ca2cd0adc3f48f9e9ea5a6bbdf9ccc0bfade884847e484d452414c7ccffb3"
+
 [[package]]
 name = "block-buffer"
 version = "0.7.3"
@@ -785,6 +791,7 @@ name = "stdtx"
 version = "0.1.0"
 dependencies = [
  "anomaly",
+ "base64",
  "ecdsa",
  "prost-amino",
  "prost-amino-derive",
diff --git a/stdtx/Cargo.toml b/stdtx/Cargo.toml
index 4c4e0e23..5e463e15 100644
--- a/stdtx/Cargo.toml
+++ b/stdtx/Cargo.toml
@@ -16,6 +16,7 @@ circle-ci = { repository = "tendermint/kms" }
 
 [dependencies]
 anomaly = { version = "0.2", path = "../anomaly" }
+base64 = "0.12.0"
 ecdsa = { version = "0.4", features = ["k256"] }
 prost-amino = "0.5"
 prost-amino-derive = "0.5"
diff --git a/stdtx/src/address.rs b/stdtx/src/address.rs
index 51f0a46c..09d8e49a 100644
--- a/stdtx/src/address.rs
+++ b/stdtx/src/address.rs
@@ -2,6 +2,7 @@
 
 use crate::error::{Error, ErrorKind};
 use anomaly::ensure;
+use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
 use std::convert::TryInto;
 use subtle_encoding::bech32;
 
@@ -34,6 +35,25 @@ impl Address {
     }
 }
 
+impl Serialize for Address {
+    fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
+        let s = self.to_bech32("cosmos"); // TODO: how to generalize?
+        s.serialize(serializer)
+    }
+}
+
+impl<'de> Deserialize<'de> for Address {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let s = String::deserialize(deserializer)?;
+        let (_hrp, addr) =
+            Address::from_bech32(s).map_err(|e| de::Error::custom(format!("{:?}", e)))?;
+        Ok(addr)
+    }
+}
+
 impl AsRef<[u8]> for Address {
     fn as_ref(&self) -> &[u8] {
         &self.0
diff --git a/stdtx/src/amino_types.rs b/stdtx/src/amino_types.rs
index e1681d46..7f272749 100644
--- a/stdtx/src/amino_types.rs
+++ b/stdtx/src/amino_types.rs
@@ -3,6 +3,9 @@
 use crate::{Signature, TypeName};
 use prost_amino::{encode_length_delimiter, Message};
 use prost_amino_derive::Message;
+use serde::{de::Error as _, Deserialize, Deserializer, Serialize, Serializer};
+
+use base64;
 use serde_json::json;
 
 /// StdTx Amino type
@@ -40,7 +43,7 @@ impl StdTx {
 }
 
 /// StdFee amino type
-#[derive(Clone, Message)]
+#[derive(Clone, Message, Serialize, Deserialize)]
 pub struct StdFee {
     /// Fee to be paid
     #[prost_amino(message, repeated, tag = "1")]
@@ -48,9 +51,28 @@ pub struct StdFee {
 
     /// Gas requested for transaction
     #[prost_amino(uint64)]
+    #[serde(serialize_with = "serialize_u64", deserialize_with = "parse_u64")]
     pub gas: u64,
 }
 
+/// Serialize u64 as a string for proto3 JSON encoding.
+pub(crate) fn serialize_u64<S>(value: &u64, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    format!("{}", value).serialize(serializer)
+}
+
+/// Parse u64 from a string for proto3 JSON decoding.
+pub(crate) fn parse_u64<'de, D>(deserializer: D) -> Result<u64, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    String::deserialize(deserializer)?
+        .parse::<u64>()
+        .map_err(|e| D::Error::custom(format!("{}", e)))
+}
+
 impl StdFee {
     /// Create a [`StdFee`] for a gas-only transaction
     pub fn for_gas(gas: u64) -> Self {
@@ -75,7 +97,7 @@ impl StdFee {
 }
 
 /// Coin Amino type
-#[derive(Clone, Message)]
+#[derive(Clone, Message, Serialize, Deserialize)]
 pub struct Coin {
     /// Denomination of coin
     #[prost_amino(string, tag = "1")]
@@ -97,21 +119,41 @@ impl Coin {
 }
 
 /// StdSignature amino type
-#[derive(Clone, Message)]
+#[derive(Clone, Message, Serialize, Deserialize)]
 pub struct StdSignature {
     /// Public key which can verify this signature
     #[prost_amino(bytes, tag = "1", amino_name = "tendermint/PubKeySecp256k1")]
-    pub pub_key: Vec<u8>,
+    #[serde(serialize_with = "serialize_base64", deserialize_with = "parse_base64")]
+    pub public_key: Vec<u8>,
 
     /// Serialized signature
     #[prost_amino(bytes)]
+    #[serde(serialize_with = "serialize_base64", deserialize_with = "parse_base64")]
     pub signature: Vec<u8>,
 }
 
+/// Serialize bytes as base64 string for proto3 JSON encoding.
+pub(crate) fn serialize_base64<S>(value: &[u8], serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    serializer.serialize_str(&base64::encode(value))
+}
+
+/// Parse bytes from a base64 string for proto3 JSON decoding.
+pub(crate) fn parse_base64<'de, D>(deserializer: D) -> Result<Vec<u8>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    String::deserialize(deserializer).and_then(|string| {
+        base64::decode(&string).map_err(|err| D::Error::custom(format!("{}", err)))
+    })
+}
+
 impl From<Signature> for StdSignature {
     fn from(signature: Signature) -> StdSignature {
         StdSignature {
-            pub_key: vec![],
+            public_key: vec![],
             signature: signature.as_ref().to_vec(),
         }
     }