Woleet documents downloadable proof receipts, OriginStamp offers an API for timestamping file hashes, and OpenTimestamps provides open-source proof tools. Test portability by asking a reviewer to verify the archived file and proof without signing in to the original service. A timestamp alone does not establish authorship or approval.
A timestamp can help show that a particular file existed by a certain time. It cannot show who approved the file or whether its contents are true. For a document archive, the buying question is what a reviewer can still verify after the original service is gone.
| Option | Documented starting point | Ask to see |
|---|---|---|
| Woleet | API for creating proofs and obtaining proof receipts | A receipt you can retain with the original file and verify without an active API account |
| OriginStamp | API documentation for timestamping hashes | A complete export for one timestamp and the instructions needed to verify it independently |
| OpenTimestamps | Open-source tools and a proof format | A completed proof that a second reviewer can check using independent tooling |
Run a vendor exit test
Take a synthetic signed PDF and archive the exact bytes, the proof and verification instructions. Record when you requested the timestamp and when the proof became verifiable. Those can be different times. Have a reviewer who has never logged in to your account verify the archived file. Then have them change a byte in a copy and verify that the original proof no longer matches.
Plan for proof retrieval and retention
Ask what happens if anchoring is delayed and whether the application must poll for a completed receipt. Check whether document bytes ever leave your environment or whether only a digest is submitted. Keep the original file and its receipt together, but manage access separately from any public anchor. If the workflow also needs identity or consent evidence, retain those records alongside the timestamp.
Documentation
Test whether you can verify after cancelling
Timestamp the same file with each option and export everything needed to prove it later. Hand the file and proof to a colleague without access to your account. Ask them to identify which verifier they need, what time claim they can independently establish and whether an account or API call is required. Change one byte and confirm that the proof no longer verifies against that copy.
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