diff --git a/packages/launchpad/src/encoding.spec.ts b/packages/launchpad/src/encoding.spec.ts
index ccdb8a4a..1ac93c9c 100644
--- a/packages/launchpad/src/encoding.spec.ts
+++ b/packages/launchpad/src/encoding.spec.ts
@@ -1 +1,50 @@
-describe("encoding", () => {});
+import { sortedJsonStringify } from "./encoding";
+
+describe("encoding", () => {
+  describe("sortedJsonStringify", () => {
+    it("leaves non-objects unchanged", () => {
+      expect(sortedJsonStringify(true)).toEqual(`true`);
+      expect(sortedJsonStringify(false)).toEqual(`false`);
+      expect(sortedJsonStringify("aabbccdd")).toEqual(`"aabbccdd"`);
+      expect(sortedJsonStringify(75)).toEqual(`75`);
+      expect(sortedJsonStringify(null)).toEqual(`null`);
+      expect(sortedJsonStringify([5, 6, 7, 1])).toEqual(`[5,6,7,1]`);
+      expect(sortedJsonStringify([5, ["a", "b"], true, null, 1])).toEqual(`[5,["a","b"],true,null,1]`);
+    });
+
+    it("sorts objects by key", () => {
+      // already sorted
+      expect(sortedJsonStringify({})).toEqual(`{}`);
+      expect(sortedJsonStringify({ a: 3 })).toEqual(`{"a":3}`);
+      expect(sortedJsonStringify({ a: 3, b: 2, c: 1 })).toEqual(`{"a":3,"b":2,"c":1}`);
+
+      // not yet sorted
+      expect(sortedJsonStringify({ b: 2, a: 3, c: 1 })).toEqual(`{"a":3,"b":2,"c":1}`);
+      expect(sortedJsonStringify({ aaa: true, aa: true, a: true })).toEqual(
+        `{"a":true,"aa":true,"aaa":true}`,
+      );
+    });
+
+    it("sorts nested objects", () => {
+      // already sorted
+      expect(sortedJsonStringify({ x: { y: { z: null } } })).toEqual(`{"x":{"y":{"z":null}}}`);
+
+      // not yet sorted
+      expect(sortedJsonStringify({ b: { z: true, x: true, y: true }, a: true, c: true })).toEqual(
+        `{"a":true,"b":{"x":true,"y":true,"z":true},"c":true}`,
+      );
+    });
+
+    it("sorts objects in arrays", () => {
+      // already sorted
+      expect(sortedJsonStringify([1, 2, { x: { y: { z: null } } }, 4])).toEqual(
+        `[1,2,{"x":{"y":{"z":null}}},4]`,
+      );
+
+      // not yet sorted
+      expect(sortedJsonStringify([1, 2, { b: { z: true, x: true, y: true }, a: true, c: true }, 4])).toEqual(
+        `[1,2,{"a":true,"b":{"x":true,"y":true,"z":true},"c":true},4]`,
+      );
+    });
+  });
+});
diff --git a/packages/launchpad/src/encoding.ts b/packages/launchpad/src/encoding.ts
index 81bafa2f..6090cc79 100644
--- a/packages/launchpad/src/encoding.ts
+++ b/packages/launchpad/src/encoding.ts
@@ -5,24 +5,30 @@ import { Uint53 } from "@cosmjs/math";
 import { Msg } from "./msgs";
 import { StdFee } from "./types";
 
-function sortJson(json: any): any {
-  if (typeof json !== "object" || json === null) {
-    return json;
+function sortedObject(obj: any): any {
+  if (typeof obj !== "object" || obj === null) {
+    return obj;
   }
-  if (Array.isArray(json)) {
-    return json.map(sortJson);
+  if (Array.isArray(obj)) {
+    return obj.map(sortedObject);
   }
-  const sortedKeys = Object.keys(json).sort();
+  const sortedKeys = Object.keys(obj).sort();
   const result = sortedKeys.reduce(
     (accumulator, key) => ({
       ...accumulator,
-      [key]: sortJson(json[key]),
+      [key]: sortedObject(obj[key]),
     }),
     {},
   );
   return result;
 }
 
+/** Returns a JSON string with objects sorted by key */
+// eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
+export function sortedJsonStringify(obj: any): string {
+  return JSON.stringify(sortedObject(obj));
+}
+
 /**
  * The document to be signed
  *
@@ -56,6 +62,5 @@ export function makeSignDoc(
 }
 
 export function serializeSignDoc(signDoc: StdSignDoc): Uint8Array {
-  const sortedSignDoc = sortJson(signDoc);
-  return toUtf8(JSON.stringify(sortedSignDoc));
+  return toUtf8(sortedJsonStringify(signDoc));
 }
diff --git a/packages/launchpad/types/encoding.d.ts b/packages/launchpad/types/encoding.d.ts
index 05f8d8ce..0cad6f04 100644
--- a/packages/launchpad/types/encoding.d.ts
+++ b/packages/launchpad/types/encoding.d.ts
@@ -1,5 +1,7 @@
 import { Msg } from "./msgs";
 import { StdFee } from "./types";
+/** Returns a JSON string with objects sorted by key */
+export declare function sortedJsonStringify(obj: any): string;
 /**
  * The document to be signed
  *