stampthisfile

stampthisfile MCP server

A hosted MCP server that lets AI agents timestamp files in Bitcoin with stampthisfile: send the SHA-256 hash of a file (never the file), pay per hash in USDC with x402, and get a standard OpenTimestamps .ots proof that anyone can verify without us. No account or API key.

• Endpoint: https://stampthisfile.com/mcp (Streamable HTTP, stateless)
• Auth: none. Stamping is paid per call with x402; everything else is free.

There is nothing to install or run: this repository describes the hosted server. The server itself is not open source.

Connect

Claude Code:

claude mcp add --transport http stampthisfile https://stampthisfile.com/mcp

Cursor, VS Code and other clients (.mcp.json style):

{
  "mcpServers": {
    "stampthisfile": {
      "type": "http",
      "url": "https://stampthisfile.com/mcp"
    }
  }
}

Tools

A proof is pending at first and completes once Bitcoin confirms it, usually within 1-6 hours. A complete proof shows the file existed no later than the time of its Bitcoin block. It is not a signature and does not show who made the file: read stampthisfile.com/evidence.md before stamping something meant as evidence.

Pricing

Stamping costs a fixed price per hash, in USDC on Base, paid with x402 using the MCP transport: without a payment, stamp_hashes returns a tool error whose structuredContent is the x402 PaymentRequired. Retry with the signed PaymentPayload in _meta["x402/payment"], or in the payment argument if your client cannot set _meta. The settlement comes back in _meta["x402/payment-response"]. Invalid input is never charged. Reading, downloading and verifying proofs are free.

More

• stampthisfile.com/llms.txt: the API for agents
• stampthisfile.com/openapi.json: REST API
• stampthisfile/skills: the same, as agent skills (npx skills add stampthisfile/skills)

License

MIT, for the contents of this repository.