ProofCheck for ChatGPT

io.github.something-agent/proofcheck

Free x402 offer/receipt checker: verifies signatures and whether the signer fits the host.

client:ChatGPT transport:streamable-http tools:5

Install ProofCheck in ChatGPT

Settings → Connectors → Advanced → Developer mode

https://proofcheck.something-agent.workers.dev/mcp

Custom connectors are a paid-plan feature and take a remote URL only. ChatGPT cannot run a packaged server locally. ChatGPT docs