x402 · Base + Solana · for builders and agents

Check any x402 endpoint the way a paying agent would.

Paste an x402-payable endpoint URL, HTTP or MCP. Read-only diagnostics: no wallet, no payment, no risk. Try an example.

Decoded challenge

New: the paid fix, in 70 seconds

See it in 70 seconds

Checks the 402 challenge and its envelope, protocol version, every accepts[] option (network, asset, amount, payee, fee payer, EIP-712 domain), the resource URL and metadata, the Solana payout token account and facilitator, Bazaar discovery (including replaying the declared example), /openapi.json and the browser paywall.

In CI or a terminal: npx github:Fizzl13/x402-doctor <url> (exits 1 on failures).

x402 Trust Index: a daily check of every x402 resource in the CDP Bazaar and its 30-day track record.

For agents: GET /api/v1/diagnose?url=<endpoint>, $0.01 USDC per call via x402 on Base or Solana, no rate limit (OpenAPI).

As an MCP server: https://x402-doctor.onrender.com/mcp, with a free quick check. Also on Smithery and Agentic Market.

Built while shipping PlainText, Ichimoku Signal and presign-guard — every check traces back to a bug that broke one of them.

presign-guard: before an agent or wallet signs a permit, approval or x402 payment, it gives a green, orange or red verdict with the reasons: unlimited amounts, long-lived permissions, flagged spenders, and the token itself (honeypots, fakes of known tokens such as a fake USDC, owner powers, high taxes). From $0.01 per check via x402 on Base.

Check any x402 endpoint the way a paying agent would.

Get the fix: $0.05

New: the paid fix, in 70 seconds

See it in 70 seconds

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