Anchoring Verify

Checks an OpenTimestamps Bitcoin-anchoring proof (.ots) entirely in this browser tab. No account, no upload — the only network requests are to the Bitcoin block explorer configured below. By default, verification trusts that explorer's own report of each block's height, merkle root, and confirmations; turn on the "local, self-validated Bitcoin header check" in Advanced settings to instead independently re-verify proof-of-work, difficulty, and hash-linkage back to a pinned checkpoint yourself — trusting nothing but math, at the cost of a slower first run.

Verify a proof

Original file (optional)

Drop the file that was hashed — confirms the proof is bound to these exact bytes.

.ots proof (required)

The proof file downloaded alongside the anchored hash.

or, if you don't have the original file

Advanced settings

Bitcoin block explorer(s), one per line, tried in order

Perform a local, self-validated Bitcoin header check (slower — may take minutes on first run; independently re-verifies proof-of-work and difficulty instead of trusting the block explorer's response). Off by default, which trusts the block explorer's own report of each block's height, merkle root, and confirmations.

Verify batch inclusion (advanced)

For a hash anchored via a batch submission: paste the hash, nonce, leaf and path returned at anchor time to recompute the batch's Merkle root independently of any other submitter's data — then verify that root's own .ots proof above.

Paste the origin object, e.g. {"hash":"sha256:...","nonce":"...","leaf":"...","path":[...]}