Proofline
Machine-payable document-integrity verification for autonomous AP agents
Demo
About
Proofline is a machine-payable document-integrity verification service for autonomous AP and financial agents. A consuming agent submits an invoice to Proofline and must pay a 0.02 HBAR verification fee through x402 on Hedera before the service performs its analysis. Proofline extracts and validates invoice fields, runs deterministic forensic checks for anomalies such as amount mismatches, unfamiliar beneficiary accounts, and document revision signals, then returns an evidence-backed CLEAR or REVIEW decision. CLEAR allows the consuming agent to proceed, while REVIEW forces it to halt the invoice payment. The verification request, payment, analysis, and agent action are presented as one auditable workflow. The downstream supplier payment is simulated; the real on-chain component is the Hedera-settled verification payment.
How it's made
Proofline is built as a full-stack service with a React/TypeScript frontend, Node/TypeScript gateway, and Python/FastAPI forensic analysis service. The gateway exposes the x402-protected verification endpoint and uses the Hedera x402 integration with the Blocky402 facilitator to require and settle a 0.02 HBAR payment on Hedera testnet. A server-side reference AP agent acts as the consuming agent, signs the payment, calls the protected service, receives the verification result, and deterministically decides whether to proceed or halt. Document analysis uses PDF/OCR extraction, structured field normalization, and deterministic forensic rules, with evidence codes and policy scoring rather than an AI-generated fraud verdict. Verification state and results are persisted in SQLite, while raw documents and OCR text remain transient. The frontend streams the real workflow through SSE, including payment, analysis, decision, and agent-action stages.