Verify · Browser-side

Verify OTS Proof

Verify any .ots timestamp proof from any source — including files stamped on opentimestamps.org, this service, or the CLI tool. Verification runs in your browser using the OpenTimestamps protocol. If the proof has been upgraded, the latest .ots will be available for download.

1. Original file

Drop original file or click to browse

SHA-256 computed locally

2. OTS proof file

Drop .ots file or click to browse

Any .ots from any source

1. SHA-256 hash
2. OTS proof file

Drop .ots file or click to browse

How it works:
  1. Compute the SHA-256 of your original file (done in browser).
  2. Parse the .ots proof and extract the OpenTimestamps operations.
  3. Attempt to upgrade any pending attestations by contacting calendar servers.
  4. Verify the proof against Bitcoin block explorers.
  5. If verified, displays the Bitcoin block height and timestamp.

Privacy: Your file never leaves the browser — only the proof metadata is sent to public calendar servers and block explorers for verification.