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Verify your timestamp proof in seconds

Upload your original file alongside its .ots proof — we check the cryptographic hash and confirm the Bitcoin blockchain record. Your file never leaves your browser.

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Files stay in your browser · No account required · Free forever

Why use this verifier?

Files never leave your browser

Your files are hashed locally. Only a 32-byte fingerprint is compared against the .ots proof — your document never touches our servers.

Bitcoin blockchain verified

Each .ots proof is checked against the Bitcoin blockchain — the most tamper-resistant ledger in existence. Verified timestamps show the exact block date and height.

Verify multiple files at once

Drop a batch of files and their .ots proofs together. Smart auto-matching pairs each file with its proof by name, so you can verify ten files as easily as one.

Fix mismatches with drag-and-drop

If filenames don't follow the standard convention, the match editor lets you drag and drop to reassign any file to its correct proof — no guessing, no re-uploads.

Full status for every file

See at a glance which files are verified with a Bitcoin date, which are still pending blockchain confirmation, and which have a hash mismatch.

Results in seconds

Hashing happens instantly in your browser. The blockchain lookup typically returns in 2–5 seconds, even for large batches.

Why you might need to verify a timestamp proof

Confirming a document predated a dispute

You timestamped a contract months ago and now there's a disagreement about when it was finalized. You have the original file and the .ots proof, but you need to confirm the timestamp is genuine — not just take it on faith.

You drop both files onto the verifier. In a few seconds, the result shows a green "Verified" badge with the exact Bitcoin block date and block height. The timestamp is anchored to the blockchain — mathematically impossible to forge. You screenshot the result and share it with your legal team.

It doesn't matter that you used a third-party timestamping service. The .ots format is an open standard — anyone can verify it independently, and that's exactly what this tool does.

Auditing a batch of proofs before an important filing

You're an IP attorney and a client has sent you 15 files and 15 .ots proofs, claiming each document existed before a specific date. You need to verify all of them before including them in a filing.

You drop all 30 files onto the verifier at once. The tool auto-matches each document to its proof by filename. Two of the matches are wrong — you fix them with a quick drag and drop. Then you hit verify.

Within seconds you have a full status table: 13 files verified with Bitcoin dates, 1 pending (recent submission, not yet confirmed on-chain), and 1 mismatch — the client sent the wrong version of a file. You ask them to resend the correct original. No manual cross-referencing, no command-line tools, no Bitcoin node required.

1

Upload your files and proofs

Drop your original files alongside their .ots proof files. You can verify multiple pairs at once.

2

Match files to their proofs

The tool auto-pairs files by name. Drag and drop to fix any mismatches before verifying.

3

See the blockchain result

Each file gets a status: Verified (with Bitcoin date), Pending, Mismatch, or Error.

  • Your files never leave your browser — there's nothing for us to delete.
  • We never see, store, or share your files. Only a 32-byte hash is compared server-side.
  • No sign-up needed. Drop your files and verify instantly.