BuildProof: verify a document

Drop a contract, supplementary agreement or acceptance act. Your browser computes its SHA-256 locally; only the hash is sent to the blockchain node. The file itself is never uploaded.

Try it in one click (Base mainnet, synthetic demo documents)

Each button downloads the sample from this site, hashes it in your browser and looks the hash up on-chain. Files: act_01.pdf, act_01_tampered.pdf (23,600.00 changed to 28,600.00), ai_review_manifest.json.

Network

Registry contract

RPC URL

Drop a file here or click to choose

PDF or any other file. Nothing leaves your computer except its hash.

or paste a SHA-256 hash Expected signers (optional): one address per line, optionally followed by a name

Sign as a party (no gas)

Open the attestation id you were sent, check that the document hash matches your copy, then sign with your wallet. You get a signature file; anyone (for example the other party) can submit it with buildproof relay.

Attestation id