MCP server for local transaction signing on EVM, UTXO, Tron, and XRP — no API calls needed
About
MCP server for local transaction signing on EVM, UTXO, Tron, and XRP — no API calls needed
Security Report
Valid MCP server (2 strong, 3 medium validity signals). 2 code issues detected. No known CVEs in dependencies. Package registry verified. Imported from the Official MCP Registry. Trust signals: trusted author (14/14 approved). 2 finding(s) downgraded by scanner intelligence.
12 files analyzed · 3 issues found
Security scores are indicators to help you make informed decisions, not guarantees. Always review permissions before connecting any MCP server.
Permissions Required
This plugin requests these system permissions. Most are normal for its category.
How to Install
Add this to your MCP configuration file:
{
"mcpServers": {
"io-github-cryptoapis-io-mcp-signer": {
"args": [
"-y",
"@cryptoapis-io/mcp-signer"
],
"command": "npx"
}
}
}Getting Started
Once installed, try these example prompts and explore these capabilities:
- 1"Sign an Ethereum transaction to 0xABC... for 0.1 ETH with my private key"
- 2"Sign a Bitcoin transaction from my prepared inputs and outputs"
- 3"Sign an XRP payment transaction offline"
- 4Tool: evm_sign — Signs EVM transactions (Ethereum, BSC, Polygon, Arbitrum, Base, Optimism, Avalanche)
- 5Tool: utxo_sign — Signs Bitcoin, Litecoin, Dogecoin, Dash, Zcash transactions
- 6Tool: tron_sign — Signs Tron transactions locally using secp256k1
- 7Tool: xrp_sign — Signs XRP transactions from structured fields or unsigned hex
Documentation
View on GitHubFrom the project's GitHub 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/secretas parameters. Keys are never read from environment variables. - No network calls — all signing is done locally using cryptographic libraries.
Installation
npm install @cryptoapis-io/mcp-signer
Or install all Crypto APIs MCP servers: npm install @cryptoapis-io/mcp
Usage
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):
{
"mcpServers": {
"cryptoapis-signer": {
"command": "npx",
"args": ["-y", "@cryptoapis-io/mcp-signer"]
}
}
}
Cursor
Add to .cursor/mcp.json (project) or ~/.cursor/mcp.json (global):
{
"mcpServers": {
"cryptoapis-signer": {
"command": "npx",
"args": ["-y", "@cryptoapis-io/mcp-signer"]
}
}
}
MCP Inspector
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
Reviews
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Version History
Dependency updates and stability improvements.
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