diff --git a/packages/proto-signing/src/signing.spec.ts b/packages/proto-signing/src/signing.spec.ts
new file mode 100644
index 00000000..31659d82
--- /dev/null
+++ b/packages/proto-signing/src/signing.spec.ts
@@ -0,0 +1,173 @@
+/* eslint-disable @typescript-eslint/naming-convention */
+import { Bech32, fromBase64, fromHex, toHex } from "@cosmjs/encoding";
+import { Secp256k1Wallet } from "@cosmjs/launchpad";
+
+import { cosmos } from "./generated/codecimpl";
+import { defaultRegistry } from "./msgs";
+import { Registry, TxBodyValue } from "./registry";
+
+const { AuthInfo, SignDoc, Tx, TxBody } = cosmos.tx;
+const { PublicKey } = cosmos.crypto;
+
+export function pendingWithoutSimapp(): void {
+  if (!process.env.SIMAPP_ENABLED) {
+    return pending("Set SIMAPP_ENABLED to enable Simapp based tests");
+  }
+}
+
+const faucet = {
+  mnemonic:
+    "economy stock theory fatal elder harbor betray wasp final emotion task crumble siren bottom lizard educate guess current outdoor pair theory focus wife stone",
+  pubkey: {
+    type: "tendermint/PubKeySecp256k1",
+    value: "A08EGB7ro1ORuFhjOnZcSgwYlpe0DSFjVNUIkNNQxwKQ",
+  },
+  address: "cosmos1pkptre7fdkl6gfrzlesjjvhxhlc3r4gmmk8rs6",
+};
+
+// Test vectors were generated using this command with Ethan’s custom fork of Cosmos-SDK with printf:
+// simd tx bank send --sign-mode direct --chain-id simd-testing testgen cosmos1qypqxpq9qcrsszg2pvxq6rs0zqg3yyc5lzv7xu 1234567ucosm -b block
+const testVectors = [
+  {
+    sequenceNumber: undefined, // Go doesn’t encode 0
+    signedTxBytes:
+      "0a580a560a142f636f736d6f732e62616e6b2e4d736753656e64123e0a140d82b1e7c96dbfa42462fe612932e6bff111d51b12140102030405060708090a0b0c0d0e0f10111213141a100a0575636f736d12073132333435363712330a2b0a230a21034f04181eeba35391b858633a765c4a0c189697b40d216354d50890d350c7029012040a020801120410c09a0c1a40692d88f681d5d69924a53668e8ecec535ca0ca170d1febfb1dd87de9959b07340427d6bba22526d6c30cc622f27dc5eb1ce04cfc0ff98716154066ec69db62e5",
+    signBytes:
+      "0a580a560a142f636f736d6f732e62616e6b2e4d736753656e64123e0a140d82b1e7c96dbfa42462fe612932e6bff111d51b12140102030405060708090a0b0c0d0e0f10111213141a100a0575636f736d12073132333435363712330a2b0a230a21034f04181eeba35391b858633a765c4a0c189697b40d216354d50890d350c7029012040a020801120410c09a0c1a0c73696d642d74657374696e672001",
+    signature:
+      "692d88f681d5d69924a53668e8ecec535ca0ca170d1febfb1dd87de9959b07340427d6bba22526d6c30cc622f27dc5eb1ce04cfc0ff98716154066ec69db62e5",
+  },
+
+  {
+    sequenceNumber: 1,
+    signedTxBytes:
+      "0a580a560a142f636f736d6f732e62616e6b2e4d736753656e64123e0a140d82b1e7c96dbfa42462fe612932e6bff111d51b12140102030405060708090a0b0c0d0e0f10111213141a100a0575636f736d12073132333435363712330a2b0a230a21034f04181eeba35391b858633a765c4a0c189697b40d216354d50890d350c7029012040a020801120410c09a0c1a40811c3c7dd85b1478b15e3cc710503045559d805d2bf538e5015dbcd868a440a94c7fc0b12b755a838cc3f9b8245d9f926e0432d07ee97557cff7c50c73f64a58",
+    signBytes:
+      "0a580a560a142f636f736d6f732e62616e6b2e4d736753656e64123e0a140d82b1e7c96dbfa42462fe612932e6bff111d51b12140102030405060708090a0b0c0d0e0f10111213141a100a0575636f736d12073132333435363712330a2b0a230a21034f04181eeba35391b858633a765c4a0c189697b40d216354d50890d350c7029012040a020801120410c09a0c1a0c73696d642d74657374696e6720012801",
+    signature:
+      "811c3c7dd85b1478b15e3cc710503045559d805d2bf538e5015dbcd868a440a94c7fc0b12b755a838cc3f9b8245d9f926e0432d07ee97557cff7c50c73f64a58",
+  },
+
+  {
+    sequenceNumber: 2,
+    signedTxBytes:
+      "0a580a560a142f636f736d6f732e62616e6b2e4d736753656e64123e0a140d82b1e7c96dbfa42462fe612932e6bff111d51b12140102030405060708090a0b0c0d0e0f10111213141a100a0575636f736d12073132333435363712330a2b0a230a21034f04181eeba35391b858633a765c4a0c189697b40d216354d50890d350c7029012040a020801120410c09a0c1a405e2e11567c181db4f38788ff6d417b1f7d147f3d6bd8274989bf181c35b3fb97218f64172030dd5a84dd38933765609d70771cbba60168d8ded611f14ec4fb12",
+    signBytes:
+      "0a580a560a142f636f736d6f732e62616e6b2e4d736753656e64123e0a140d82b1e7c96dbfa42462fe612932e6bff111d51b12140102030405060708090a0b0c0d0e0f10111213141a100a0575636f736d12073132333435363712330a2b0a230a21034f04181eeba35391b858633a765c4a0c189697b40d216354d50890d350c7029012040a020801120410c09a0c1a0c73696d642d74657374696e6720012802",
+    signature:
+      "5e2e11567c181db4f38788ff6d417b1f7d147f3d6bd8274989bf181c35b3fb97218f64172030dd5a84dd38933765609d70771cbba60168d8ded611f14ec4fb12",
+  },
+];
+
+describe("signing demo", () => {
+  const chainId = "simd-testing";
+  const toAddress = Uint8Array.from({ length: 20 }, (_, i) => i + 1);
+
+  const sendAmount = "1234567";
+  const sendDenom = "ucosm";
+  const gasLimit = 200000;
+
+  it("correctly parses test vectors", async () => {
+    const wallet = await Secp256k1Wallet.fromMnemonic(faucet.mnemonic);
+    const [{ address, pubkey: pubkeyBytes }] = await wallet.getAccounts();
+
+    testVectors.forEach(({ signedTxBytes }) => {
+      const parsedTestTx = Tx.decode(fromHex(signedTxBytes));
+      expect(parsedTestTx.signatures.length).toEqual(1);
+      expect(parsedTestTx.authInfo?.signerInfos?.length).toEqual(1);
+      expect(parsedTestTx.authInfo?.signerInfos![0].publicKey!.secp256k1).toEqual(pubkeyBytes);
+      expect(parsedTestTx.authInfo?.signerInfos![0].modeInfo!.single!.mode).toEqual(
+        cosmos.tx.signing.SignMode.SIGN_MODE_DIRECT,
+      );
+      expect(parsedTestTx.authInfo?.fee!.amount).toEqual([]);
+      expect(parsedTestTx.authInfo?.fee!.gasLimit!.toString()).toEqual(gasLimit.toString());
+      expect(parsedTestTx.body?.extensionOptions).toEqual([]);
+      expect(parsedTestTx.body?.nonCriticalExtensionOptions).toEqual([]);
+      expect(parsedTestTx.body!.messages!.length).toEqual(1);
+
+      const parsedTestTxMsg = defaultRegistry.decode({
+        typeUrl: parsedTestTx.body!.messages![0].type_url!,
+        value: parsedTestTx.body!.messages![0].value!,
+      });
+      expect(parsedTestTxMsg.from_address).toEqual(Bech32.decode(address).data);
+      expect(parsedTestTxMsg.to_address).toEqual(toAddress);
+      expect(parsedTestTxMsg.amount.length).toEqual(1);
+      expect(parsedTestTxMsg.amount[0].denom).toEqual(sendDenom);
+      expect(parsedTestTxMsg.amount[0].amount).toEqual(sendAmount);
+    });
+  });
+
+  it("correctly generates test vectors", async () => {
+    const myRegistry = new Registry();
+    const wallet = await Secp256k1Wallet.fromMnemonic(faucet.mnemonic);
+    const [{ address, pubkey: pubkeyBytes }] = await wallet.getAccounts();
+    const publicKey = PublicKey.create({
+      secp256k1: pubkeyBytes,
+    });
+
+    const txBodyFields: TxBodyValue = {
+      messages: [
+        {
+          typeUrl: "/cosmos.bank.MsgSend",
+          value: {
+            fromAddress: Bech32.decode(address).data,
+            toAddress: toAddress,
+            amount: [
+              {
+                denom: sendDenom,
+                amount: sendAmount,
+              },
+            ],
+          },
+        },
+      ],
+    };
+    const txBodyBytes = myRegistry.encode({
+      typeUrl: "/cosmos.tx.TxBody",
+      value: txBodyFields,
+    });
+    const txBody = TxBody.decode(txBodyBytes);
+
+    const authInfo = {
+      signerInfos: [
+        {
+          publicKey: publicKey,
+          modeInfo: {
+            single: {
+              mode: cosmos.tx.signing.SignMode.SIGN_MODE_DIRECT,
+            },
+          },
+        },
+      ],
+      fee: {
+        gasLimit: gasLimit,
+      },
+    };
+    const authInfoBytes = Uint8Array.from(AuthInfo.encode(authInfo).finish());
+    const accountNumber = 1;
+
+    await Promise.all(
+      testVectors.map(async ({ sequenceNumber, signBytes, signedTxBytes }) => {
+        const signDoc = SignDoc.create({
+          bodyBytes: txBodyBytes,
+          authInfoBytes: authInfoBytes,
+          chainId: chainId,
+          accountNumber: accountNumber,
+          accountSequence: sequenceNumber,
+        });
+        const signDocBytes = Uint8Array.from(SignDoc.encode(signDoc).finish());
+        expect(toHex(signDocBytes)).toEqual(signBytes);
+
+        const signature = await wallet.sign(address, signDocBytes);
+        const txRaw = Tx.create({
+          body: txBody,
+          authInfo: authInfo,
+          signatures: [fromBase64(signature.signature)],
+        });
+        const txRawBytes = Uint8Array.from(Tx.encode(txRaw).finish());
+        const txBytesHex = toHex(txRawBytes);
+        expect(txBytesHex).toEqual(signedTxBytes);
+      }),
+    );
+  });
+});