Countersign for ChatGPT

ai.llpro.countersign/countersign

Independent, signed check of AI work: math, quotes, sources, links, code. Public verifiable log.

client:ChatGPT transport:streamable-http tools:3

Install Countersign in ChatGPT

Settings → Connectors → Advanced → Developer mode

https://countersign.llpro.ai/mcp

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