io.github.CryptoAPIs-io/mcp-signer
MCP server for local transaction signing on EVM, UTXO, Tron, and XRP — no API calls needed
Open source Open in the app JSON README (API)
About
MCP server for local transaction signing on EVM, UTXO, Tron, and XRP — no API calls needed
Details
- Kind
- MCP servers
- Topic
- No topic detected
- Publisher
- cryptoapis-io
- Origin
- official
- Category
- ferramentas
- Transport
- local
- Version
- 0.4.0
- Last push
- 2026-07-30T05:50:10Z
- Repository state
- ativo
- Language
- TypeScript
- Added
- 2026-08-29 03:01:48
- Updated
- 2026-08-29 03:01:48
- Origin id
io.github.CryptoAPIs-io/mcp-signer
README
# @cryptoapis-io/mcp-signer
MCP server for **local transaction signing** across EVM, UTXO, Tron, and XRP blockchains. No Crypto APIs HTTP calls — signing happens entirely on your machine. No API key required.
## Security
- **Stdio only** — no HTTP transport. The server does not listen on any port.
- **Private keys in tool input** — each tool receives `privateKey` / `privateKeys` / `secret` as parameters. Keys are never read from environment variables.
- **No network calls** — all signing is done locally using cryptographic libraries.
## Installation
```bash
npm install @cryptoapis-io/mcp-signer
```
Or install all Crypto APIs MCP servers: `npm install @cryptoapis-io/mcp`
## Usage
```bash
npx @cryptoapis-io/mcp-signer
```
### Claude Desktop
Add to your Claude Desktop config (`~/Library/Application Support/Claude/claude_desktop_config.json` on macOS, `%APPDATA%\Claude\claude_desktop_config.json` on Windows):
```json
{
"mcpServers": {
"cryptoapis-signer": {
"command": "npx",
"args": ["-y", "@cryptoapis-io/mcp-signer"]
}
}
}
```
### Cursor
Add to `.cursor/mcp.json` (project) or `~/.cursor/mcp.json` (global):
```json
{
"mcpServers": {
"cryptoapis-signer": {
"command": "npx",
"args": ["-y", "@cryptoapis-io/mcp-signer"]
}
}
}
```
### MCP Inspector
```bash
npx @modelcontextprotocol/inspector npx @cryptoapis-io/mcp-signer
```
## Available Tools
### `evm_sign`
Sign an EVM transaction (Ethereum, Ethereum Classic, BSC, Polygon, Avalanche (C-Chain), Arbitrum, Base, Optimism, Tron).
| Action | Description |
|--------|-------------|
| `sign-from-details` | Sign from structured transaction fields (to, value, gasLimit, etc.) |
| `sign-unsigned-hex` | Sign a pre-built unsigned transaction hex |
| `sign-typed-data` | Sign an EIP-712 typed-data message (the x402 gasless path — e.g. the EIP-3009 `TransferWithAuthorization` from the x402 buyer `/authorize`). Returns `{ signature }`, not a tx. |
### `utxo_sign`
Sign a UTXO transaction (Bitcoin, Bitcoin Cash, Litecoin, Dogecoin, Dash, Zcash).
| Action | Description |
|--------|-------------|
| `sign-from-details` | Sign from a prepared transaction object (inputs, outputs) |
| `sign-unsigned-hex` | Sign a raw unsigned transaction hex with input descriptors |
### `tron_sign`
Sign a Tron transaction using secp256k1 (no TronWeb dependency).
| Action | Description |
|--------|-------------|
| `sign-from-details` | Sign from a transaction object with `raw_data_hex` |
| `sign-unsigned-hex` | Sign a pre-built unsigned transaction hex |
### `xrp_sign`
Sign an XRP transaction.
| Action | Description |
|--------|-------------|
| `sign-from-details` | Sign from structured XRP transaction fields |
| `sign-unsigned-hex` | Sign a pre-built unsigned transaction hex |
### `kaspa_sign`
Sign a Kaspa transaction using schnorr (BIP340) via `kaspa-wasm`. Mainnet only.
| Action | Description |
|--------|-------------|
| `sign-from-details` | Sign a prepared Kaspa transaction (from the prepare-transaction API) |
### `svm_sign`
Partial-sign a Solana (SVM) x402 payment transaction — the buyer's source-authority signature only
(the facilitator's feePayer slot stays unsigned, signed at settle).
| Action | Description |
|--------|-------------|
| `partial-sign` | Deserialize the base64 unsigned TransferChecked tx from the x402 buyer `/authorize` (scheme `svm-transaction`), add the buyer signature, re-serialize to base64. Returns `{ transaction }`. |
Most tools return `signedTransactionHex` — ready to broadcast with `@cryptoapis-io/mcp-broadcast`. The
x402 paths return `{ signature }` (EVM typed-data) or `{ transaction }` (SVM) instead.
## Dependencies
| Package | Purpose |
|---------|---------|
| `ethers` | EVM transaction signing |
| `bitcoinjs-lib` + `ecpair` + `tiny-secp256k1` | UTXO transaction signing |
| `elliptic` | Tron transaction signing (secp256k1) |
| `xrpl` | XRP transaction signing |
## License
MIT