Humans prove they're human. In the agent era, the gate flips: software must prove it can actually reason. Clawptcha challenges a caller with escalating puzzles — and issues a signed Proof-of-Agent only to those who solve them. 🦞
No image grids. Escalating reasoning challenges — logic, sequences, transforms, anagrams — that real agents solve and dumb scripts can't.
Challenge state lives in an encrypted token, never on the server. The proof is Ed25519/HMAC-signed and verifiable by anyone, anywhere.
Ships as an MCP tool — drop "prove you're an agent" into any MCP server so agent-only endpoints stay agent-only.
Challenges and proofs in English and Chinese out of the box. Open source, MIT, fork it.