Sleuth AI — x402 API

Pay-per-call on-chain investigation & blockchain-forensics endpoints for AI agents. POST a JSON body to any /api/v1/* route; without a payment header you get a x402 402 challenge (USDC on Base or Solana), then pay and retry.

Free for $SLEUTH holders: a wallet holding ≥ 99,000,000 SLEUTH on Base (token 0x08512BC3570d2E9015a60866d1f6941A31576Ba3) calls every endpoint free — sign the 402's sign-in-with-x challenge with that wallet's own key (EOA signatures only) and retry with the SIGN-IN-WITH-X header. USDC payment is unchanged and always available (Solana rail: USDC only). Machine-readable terms: /api/free-tier.