Same file, years later. Prove it.
Spoliation fights and authenticity challenges (FRE 901 and 902 territory in the US, with similar rules elsewhere) turn on one question: is the file produced in court the file collected at intake? Internal hash logs answer it with the producing party's own word. Hashing at intake and notarizing that hash with a neutral witness gives you a signed, RFC 3161 timestampable fixed point that any party, including the other side, can re-verify years later with the open verifiers. The file itself never leaves your systems: hash only, zero content shared.
Hash at intake, in your browser.
Pick any file. Your browser computes its SHA-256 fingerprint locally with the Web Crypto API and shows you the exact hash you would notarize. The file is hashed in your browser and never uploaded. Nothing is stored about you.
intake record (JSON)
curl -X POST https://dynamicfeed.ai/v1/notarize -H "content-type: application/json" -H "X-API-Key: YOUR_FREE_KEY" -d '{"hash":"sha256:<your hash>","ref":"matter-<id>-intake"}'
The returned receipt is Ed25519-signed and RFC 3161 timestampable. Re-verify it any time against /.well-known/keys or with the MIT-licensed verifiers on PyPI, npm and crates.io (see /verify and /standards). A free key is self-serve at POST /signup, details in the docs.
Authenticity challenges are decided on records.
When a production is challenged, the internal hash log is necessary but it is the producing party's own record, kept on the producing party's own systems, and the other side will say exactly that. A hash notarized at intake by an independent witness, signed at the moment, retained in the signed archive, and re-verifiable years later against a published key, is corroboration that does not depend on anyone taking your word for it. Our records work against us just as well as they work for you: anyone can re-check them, including opposing counsel.
Evidence, not a custody chain by itself.
Dynamic Feed is a neutral witness, not a court, certifier or adviser. A notarized hash proves that this exact byte sequence existed at notarization time and has not changed since. It does not authenticate who created the file, and it does not establish the whole chain of custody by itself: custody logs, collection method and affidavits remain the parties' responsibility, and a human affiant may still be required by the court. Advisory evidence beside your custody log, tamper-evident not tamper-proof, not a certification and not legal advice.
One API call per evidence item.
Collection tooling can mint a signed custody receipt for every item at intake automatically, hash only, self-serve to scale.