Summary
Routes blockchain transactions through your actual browser wallet instead of asking for private keys in config files. Exposes MCP tools for EVM chains (MetaMask, Rabby) via EIP-6963 and TRON via TronLink. You get connect_wallet, send_transaction, sign_message, sign_typed_data, plus balance lookups that work without opening a browser. Each signing operation spawns a local HTTP server and opens an approval page where you review the transaction in your wallet extension. Works with Ethereum, Polygon, Arbitrum, Base, and other EVM chains plus TRON mainnet and testnets. Reach for this when you want Claude to interact with smart contracts but need to approve every action yourself.
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Get the MCP →mcp-wallet-signer
[!WARNING] Superseded by browser-web3-signer — the same browser-wallet signing flow, reimplemented in Rust with a CLI plus Rust/TypeScript/Go libraries. Everything published from this repo is now a thin compatibility shim over it, so existing installs keep working; new code should use
browser-web3-signerdirectly.
Your private keys never leave your browser. Every transaction requires explicit approval in your own wallet (MetaMask, Rabby, TronLink, …).
Most blockchain tooling wants a private key in a config file — full, unsupervised access to your funds. These packages route each request to the browser wallet you already use, so you review and approve it like any other dapp interaction.
Packages
| Package | What it is now |
|---|---|
mcp-wallet-signer | MCP stdio server: four signing tools over browser-web3-signer |
browser-evm-signer | The old WalletSigner EVM library API, re-backed by the Rust bridge |
browser-tron-signer | The same for TRON (TronLink, TRC-20, contract deploys) |
All three spawn browser-web3-signer serve, which owns the localhost bridge, the approval page
and the browser tab. The binary for your platform is installed as a dependency; nothing else to
set up.
MCP server
claude mcp add wallet-signer -- npx -y mcp-wallet-signer
Or, for Claude Desktop / Cursor / Windsurf and any other stdio MCP client:
{
"mcpServers": {
"wallet-signer": {
"command": "npx",
"args": ["-y", "mcp-wallet-signer"]
}
}
}
| Tool | Description |
|---|---|
connect_wallet | Connect a wallet, return the address |
send_transaction | Send value or call a contract, return the tx hash |
sign_message | personal_sign a message, return the signature |
sign_typed_data | Sign EIP-712 typed data, return the signature |
EVM_MCP_DEFAULT_CHAIN sets the chain id used when a call omits one (default: 1).
Libraries
import { WalletSigner } from "browser-evm-signer";
const signer = new WalletSigner({ defaultChainId: 8453 });
const { address } = await signer.connectWallet();
const { txHash } = await signer.sendTransaction({ to: "0x…", value: "1000000000000000000" });
What changed in the shims
- Gone:
PendingStore,pendingStore,createHttpServer,startTestServer,buildConnectUrl,buildSignUrl,openBrowser— the in-process HTTP bridge they drove no longer exists. approvalUrlis now the bridge's base URL. The bridge opens the approval page itself and does not hand the per-request URL back.port(the constructor option) is ignored: the bridge binds its own free port.getPort()/DEFAULT_PORTstill resolve, for source compatibility.- MCP: the balance tools (
get_balance,get_token_balance) and the TRON tools are gone from the MCP server. Balances never needed a wallet — any RPC-reading MCP server orcast calldoes them without an approval prompt — and TRON signing is a CLI away.WalletSigner.getBalanceand.getTokenBalanceare untouched in both libraries. - Deprecated on npm and JSR.
browser-evm-signer@0.3.0never worked at all: itsexportspointed at./esm/mod.jswhile the tarball shipped./esm/browser-evm-signer/src/mod.js, which tookmcp-wallet-signer@0.6.0down with it (#2).
The pre-shim Deno implementation — the in-process bridge, the Svelte approval UI, the
wallet-signer-core package — is in the history, up to commit
636fd3b.
Development
npm install
npm test # builds, then runs each package's tests against a fake bridge
Releases are per package: tag <package>@<version> and publish a GitHub release.
License
MIT
Featured
Keeps your Mac awake while Claude Code, Codex or Cursor works. Lets it sleep when they are done.
Try free for 7 days →Block distracting apps from your iPhone permanently without a 3rd party app. Free and open source.
Block now (100% free) →Notes, actions and memory. Without a meeting bot. First month 100% off.
Download for free →belt cli automatically finds the best tools and skills for your agent. image, video, music, tts...
one prompt install →Free an open-source skills that make AI coding agents easier to understand, verify, and control.
Download for free →Connect your Claude agent to live crypto prices and trading routes via 1inch
Get the MCP →Configuration
EVM_MCP_PORTdefault: 3847HTTP server port for the browser approval UI (default: 3847)
EVM_MCP_DEFAULT_CHAINdefault: 1Default EVM chain ID (default: 1 for Ethereum mainnet)
Categories
Registryactive
Packagemcp-wallet-signer
TransportSTDIO
UpdatedFeb 10, 2026
