{
  "markdown": "# @cryptoapis-io/mcp-signer\n\nMCP 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.\n\n## Security\n\n- **Stdio only** — no HTTP transport. The server does not listen on any port.\n- **Private keys in tool input** — each tool receives `privateKey` / `privateKeys` / `secret` as parameters. Keys are never read from environment variables.\n- **No network calls** — all signing is done locally using cryptographic libraries.\n\n## Installation\n\n```bash\nnpm install @cryptoapis-io/mcp-signer\n```\n\nOr install all Crypto APIs MCP servers: `npm install @cryptoapis-io/mcp`\n\n## Usage\n\n```bash\nnpx @cryptoapis-io/mcp-signer\n```\n\n### Claude Desktop\n\nAdd to your Claude Desktop config (`~/Library/Application Support/Claude/claude_desktop_config.json` on macOS, `%APPDATA%\\Claude\\claude_desktop_config.json` on Windows):\n\n```json\n{\n  \"mcpServers\": {\n    \"cryptoapis-signer\": {\n      \"command\": \"npx\",\n      \"args\": [\"-y\", \"@cryptoapis-io/mcp-signer\"]\n    }\n  }\n}\n```\n\n### Cursor\n\nAdd to `.cursor/mcp.json` (project) or `~/.cursor/mcp.json` (global):\n\n```json\n{\n  \"mcpServers\": {\n    \"cryptoapis-signer\": {\n      \"command\": \"npx\",\n      \"args\": [\"-y\", \"@cryptoapis-io/mcp-signer\"]\n    }\n  }\n}\n```\n\n### MCP Inspector\n\n```bash\nnpx @modelcontextprotocol/inspector npx @cryptoapis-io/mcp-signer\n```\n\n## Available Tools\n\n### `evm_sign`\n\nSign an EVM transaction (Ethereum, Ethereum Classic, BSC, Polygon, Avalanche (C-Chain), Arbitrum, Base, Optimism, Tron).\n\n| Action | Description |\n|--------|-------------|\n| `sign-from-details` | Sign from structured transaction fields (to, value, gasLimit, etc.) |\n| `sign-unsigned-hex` | Sign a pre-built unsigned transaction hex |\n| `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. |\n\n### `utxo_sign`\n\nSign a UTXO transaction (Bitcoin, Bitcoin Cash, Litecoin, Dogecoin, Dash, Zcash).\n\n| Action | Description |\n|--------|-------------|\n| `sign-from-details` | Sign from a prepared transaction object (inputs, outputs) |\n| `sign-unsigned-hex` | Sign a raw unsigned transaction hex with input descriptors |\n\n### `tron_sign`\n\nSign a Tron transaction using secp256k1 (no TronWeb dependency).\n\n| Action | Description |\n|--------|-------------|\n| `sign-from-details` | Sign from a transaction object with `raw_data_hex` |\n| `sign-unsigned-hex` | Sign a pre-built unsigned transaction hex |\n\n### `xrp_sign`\n\nSign an XRP transaction.\n\n| Action | Description |\n|--------|-------------|\n| `sign-from-details` | Sign from structured XRP transaction fields |\n| `sign-unsigned-hex` | Sign a pre-built unsigned transaction hex |\n\n### `kaspa_sign`\n\nSign a Kaspa transaction using schnorr (BIP340) via `kaspa-wasm`. Mainnet only.\n\n| Action | Description |\n|--------|-------------|\n| `sign-from-details` | Sign a prepared Kaspa transaction (from the prepare-transaction API) |\n\n### `svm_sign`\n\nPartial-sign a Solana (SVM) x402 payment transaction — the buyer's source-authority signature only\n(the facilitator's feePayer slot stays unsigned, signed at settle).\n\n| Action | Description |\n|--------|-------------|\n| `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 }`. |\n\nMost tools return `signedTransactionHex` — ready to broadcast with `@cryptoapis-io/mcp-broadcast`. The\nx402 paths return `{ signature }` (EVM typed-data) or `{ transaction }` (SVM) instead.\n\n## Dependencies\n\n| Package | Purpose |\n|---------|---------|\n| `ethers` | EVM transaction signing |\n| `bitcoinjs-lib` + `ecpair` + `tiny-secp256k1` | UTXO transaction signing |\n| `elliptic` | Tron transaction signing (secp256k1) |\n| `xrpl` | XRP transaction signing |\n\n## License\n\nMIT\n",
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  "repo_slug": "cryptoapis-io/cryptoapis-mcp-signer",
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  "api": "https://agentalog.com/api/listings/mcp_io_github_cryptoapis_io_mcp_signer_705ab153/readme"
}