ExistBefore creates cryptographic proof that a specific file existed at a specific time. It is public, free, and account-less, powered by the CertiSigma trust infrastructure.
Your file stays in the browser. We compute SHA-256 locally. Nothing except the hash is transmitted.
The 64-character hex hash goes through a server-side proxy that adds the API key. The CertiSigma API never sees your original content.
You receive an immediate T0 signature, a PDF you can share, and a link to check T1 and T2 as they complete.
Network boundary: only the SHA-256 digest crosses the network. The proxy injects the API key server-side; your file bytes and the API key never meet in the browser.
T0 is created immediately. T1 and T2 strengthen the same T0 fingerprint over time; they do not require the original file to be uploaded again.
Important: T1 and T2 strengthen the same T0 fingerprint. They do not change the attested content and they do not require the original file to leave your browser.
ECDSA P-256 over the attestation payload. It proves CertiSigma registered this SHA-256 digest at T0.
Adds: an immediate signed record and a PDF receipt you can keep.
Limit: it does not prove ownership, authorship, copyright, novelty, or what the file contains.
Merkle batch + RFC 3161 TSA. A qualified timestamp is added to the same attestation record.
Adds: an independent time source from a qualified trust service provider.
Limit: it reinforces when the digest existed; it still does not certify authorship or rights.
OpenTimestamps anchors the same record to Bitcoin once confirmations are available.
Adds: public long-term verifiability that does not depend on a single operator.
Limit: Bitcoin anchors the digest timeline, not the identity, intent, or legal rights of a person.
The PDF is a human-readable container for the cryptographic data — not the root of trust itself. You can verify independently by recomputing the hash and checking the signature, or use the public API.
Read more: Digital timestamping, Proof of existence vs copyright, Technical overview.
ExistBefore is powered by the CertiSigma API — the same endpoints are available for integration into legal tech, document management, and creative tools. API documentation →