Day three of our how-to week is about evidence. If someone ever says "I never signed that", you need evidence you can show without asking anyone for it, including the company that ran the signing.
Every completed agreement on Attest comes with four pieces of evidence, on every plan.
The signed copy
One PDF with every signature, the complete evidence and an open-source verifier inside it. Every party gets the same file, decrypted only in their own browser. Its pages are anchored on Base, so a copy with a changed word fails verification.
The certificate
The certificate of completion records who signed and when, each signature's evidence, the document's fingerprint and the record anchored on Base. It is part of the signed copy, and it is also available as a live page that re-checks every signature in the visitor's browser.
The stamp
Every signature and set of initials carries a stamp with the agreement's verification code and a QR code. Scanning it opens the live certificate, so anyone holding a printed or forwarded copy can reach the evidence in one step.
The proof
Each signer gets a zero-knowledge proof that they signed, made within minutes of completion and verified on zkVerify. It proves the fact without revealing the document.
Keep them
Download the signed copy and keep it with your records. It verifies on its own, even if Attest is unavailable: the verifier inside it reads the anchor straight from the public blockchain. The guide to downloading the signed copy and certificate explains each file.
Sign your first document. Your first 2 documents are free.
Attest is part of the Horizen ecosystem on Base, and its zero-knowledge proofs are verified on zkVerify.
