Prove Any File Existed. Forever.
Drop any file. Get a permanent, Bitcoin-backed timestamp. Valid in court. No lawyers. No trust required.
Satohash hashes your file locally in your browser — your document never leaves your device. Only a cryptographic fingerprint gets written to the Bitcoin blockchain, creating immutable proof of existence for any file, contract, photo, or dataset.
Stamp a File — It's Free · Verify a proof · Pricing
How it works
- Upload or hash your file — Satohash instantly generates a SHA-256 fingerprint in your browser. Your file never leaves your device.
- Anchor to Bitcoin — Your fingerprint is submitted to the Bitcoin blockchain via OpenTimestamps, embedded in the next block, typically within 60 minutes.
- Download your certificate — Receive a portable proof certificate, independently verifiable anywhere, anytime — even if Satohash ceases to exist.
Why Bitcoin timestamping
- No server required — zero-knowledge by design, only a hash leaves your device.
- Anchored in ~60 minutes — every node on Earth validates it; it cannot be altered, backdated, or deleted.
- Court-ready evidence — satisfies ESIGN Act (US), UETA, and eIDAS (EU); mathematically non-repudiable.
- No middleman ever — Bitcoin itself is the notary, 18,000+ full nodes strong.
Who needs proof that can't be faked
Legal contracts, creative work, medical records, corporate compliance, research & IP, government & archives.