diff --git a/CHANGELOG.md b/CHANGELOG.md
index 62517f86f1..a40b46d10d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,8 @@ and this project adheres to
   available under `tendermint33`.
 - @cosmjs/proto-signing and @cosmjs/stargate: Create a Stargate-ready
   `parseCoins` that replaces the `parseCoins` re-export from `@cosmjs/amino`.
+- @cosmjs/cosmwasm-stargate: Export `isValidBuilder`, which is a clone of
+  `isValidBuilder` from @cosmjs/cosmwasm-launchpad.
 
 ### Changed
 
diff --git a/packages/cosmwasm-stargate/src/builder.spec.ts b/packages/cosmwasm-stargate/src/builder.spec.ts
new file mode 100644
index 0000000000..20926f4c82
--- /dev/null
+++ b/packages/cosmwasm-stargate/src/builder.spec.ts
@@ -0,0 +1,63 @@
+import { isValidBuilder } from "./builder";
+
+describe("builder", () => {
+  describe("isValidBuilder", () => {
+    // Valid cases
+
+    it("returns true for simple examples", () => {
+      expect(isValidBuilder("myorg/super-optimizer:0.1.2")).toEqual(true);
+      expect(isValidBuilder("myorg/super-optimizer:42")).toEqual(true);
+    });
+
+    it("supports images with multi level names", () => {
+      expect(isValidBuilder("myorg/department-x/office-y/technology-z/super-optimizer:0.1.2")).toEqual(true);
+    });
+
+    it("returns true for tags with lower and upper chars", () => {
+      expect(isValidBuilder("myorg/super-optimizer:0.1.2-alpha")).toEqual(true);
+      expect(isValidBuilder("myorg/super-optimizer:0.1.2-Alpha")).toEqual(true);
+    });
+
+    // Invalid cases
+
+    it("returns false for missing or empty tag", () => {
+      expect(isValidBuilder("myorg/super-optimizer")).toEqual(false);
+      expect(isValidBuilder("myorg/super-optimizer:")).toEqual(false);
+    });
+
+    it("returns false for name components starting or ending with a separator", () => {
+      expect(isValidBuilder(".myorg/super-optimizer:42")).toEqual(false);
+      expect(isValidBuilder("-myorg/super-optimizer:42")).toEqual(false);
+      expect(isValidBuilder("_myorg/super-optimizer:42")).toEqual(false);
+      expect(isValidBuilder("myorg./super-optimizer:42")).toEqual(false);
+      expect(isValidBuilder("myorg-/super-optimizer:42")).toEqual(false);
+      expect(isValidBuilder("myorg_/super-optimizer:42")).toEqual(false);
+      expect(isValidBuilder("myorg/.super-optimizer:42")).toEqual(false);
+      expect(isValidBuilder("myorg/-super-optimizer:42")).toEqual(false);
+      expect(isValidBuilder("myorg/_super-optimizer:42")).toEqual(false);
+      expect(isValidBuilder("myorg/super-optimizer.:42")).toEqual(false);
+      expect(isValidBuilder("myorg/super-optimizer-:42")).toEqual(false);
+      expect(isValidBuilder("myorg/super-optimizer_:42")).toEqual(false);
+    });
+
+    it("returns false for upper case character in name component", () => {
+      expect(isValidBuilder("mYorg/super-optimizer:42")).toEqual(false);
+      expect(isValidBuilder("myorg/super-Optimizer:42")).toEqual(false);
+    });
+
+    it("returns false for long images", () => {
+      expect(
+        isValidBuilder(
+          "myorgisnicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenicenice/super-optimizer:42",
+        ),
+      ).toEqual(false);
+    });
+
+    it("returns false for images with no organization", () => {
+      // Those are valid dockerhub images from https://hub.docker.com/_/ubuntu and https://hub.docker.com/_/rust
+      // but not valid in the context of CosmWasm Verify
+      expect(isValidBuilder("ubuntu:xenial-20200212")).toEqual(false);
+      expect(isValidBuilder("rust:1.40.0")).toEqual(false);
+    });
+  });
+});
diff --git a/packages/cosmwasm-stargate/src/builder.ts b/packages/cosmwasm-stargate/src/builder.ts
new file mode 100644
index 0000000000..31a790c79a
--- /dev/null
+++ b/packages/cosmwasm-stargate/src/builder.ts
@@ -0,0 +1,20 @@
+// A docker image regexp. We remove support for non-standard registries for simplicity.
+// https://docs.docker.com/engine/reference/commandline/tag/#extended-description
+//
+// An image name is made up of slash-separated name components (optionally prefixed by a registry hostname).
+// Name components may contain lowercase characters, digits and separators.
+// A separator is defined as a period, one or two underscores, or one or more dashes. A name component may not start or end with a separator.
+//
+// A tag name must be valid ASCII and may contain lowercase and uppercase letters, digits, underscores, periods and dashes.
+// A tag name may not start with a period or a dash and may contain a maximum of 128 characters.
+const dockerImagePattern = new RegExp(
+  "^[a-z0-9][a-z0-9._-]*[a-z0-9](/[a-z0-9][a-z0-9._-]*[a-z0-9])+:[a-zA-Z0-9_][a-zA-Z0-9_.-]{0,127}$",
+);
+
+/** Max length in bytes/characters (regexp enforces all ASCII, even if that is not required by the standard) */
+const builderMaxLength = 128;
+
+export function isValidBuilder(builder: string): boolean {
+  if (builder.length > builderMaxLength) return false;
+  return !!builder.match(dockerImagePattern);
+}
diff --git a/packages/cosmwasm-stargate/src/index.ts b/packages/cosmwasm-stargate/src/index.ts
index e90bbc571d..c02bdae8f0 100644
--- a/packages/cosmwasm-stargate/src/index.ts
+++ b/packages/cosmwasm-stargate/src/index.ts
@@ -1,4 +1,5 @@
 export { cosmWasmTypes } from "./aminotypes";
+export { isValidBuilder } from "./builder";
 export {
   Code,
   CodeDetails,
diff --git a/packages/cosmwasm-stargate/src/signingcosmwasmclient.ts b/packages/cosmwasm-stargate/src/signingcosmwasmclient.ts
index 8d614adc1d..f02a4f8474 100644
--- a/packages/cosmwasm-stargate/src/signingcosmwasmclient.ts
+++ b/packages/cosmwasm-stargate/src/signingcosmwasmclient.ts
@@ -1,6 +1,5 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import { encodeSecp256k1Pubkey, makeSignDoc as makeSignDocAmino } from "@cosmjs/amino";
-import { isValidBuilder } from "@cosmjs/cosmwasm-launchpad";
 import { sha256 } from "@cosmjs/crypto";
 import { fromBase64, toHex, toUtf8 } from "@cosmjs/encoding";
 import { Int53, Uint53 } from "@cosmjs/math";
@@ -47,6 +46,7 @@ import Long from "long";
 import pako from "pako";
 
 import { cosmWasmTypes } from "./aminotypes";
+import { isValidBuilder } from "./builder";
 import { CosmWasmClient } from "./cosmwasmclient";
 import {
   MsgClearAdminEncodeObject,