Proof of Existence Services Compared
By BlockchainSignPublished
We sell one of these, so read accordingly. What follows is the comparison we would want if we were buying, including the rows where we lose.
Prices and features verified 14 August 2026 from public pages.
The field
| Service | Technology | Price | Model |
|---|---|---|---|
| OpenTimestamps | Bitcoin, Merkle-batched | Free | Open protocol, CLI and library |
| FreeTSA | RFC 3161 | Free | Public timestamping authority |
| ProofStamper | RFC 3161 via FreeTSA | Free tier, paid tiers above | Browser tool for creators |
| OriginStamp | Bitcoin and Ethereum | Commercial, sales-led | API-first, enterprise |
| ScoreDetect | SKALE | ~$11.31/month for 100 certificates | Content-protection subscription |
| Bernstein | Bitcoin plus qualified TSA | From €39/month; €49 per registration | Legal-grade IP evidence |
| BlockchainSign | Ethereum, one transaction each | $9.99 for one, $3.00 each at 100 | One-off certificates |
The rows that actually differentiate
Price is the least useful comparison, because the products are not the same shape. These four matter more.
Does your file get uploaded? It should not — the hash is all a timestamp needs. OpenTimestamps, FreeTSA, ProofStamper and we all hash locally. Bernstein encrypts client-side. Always confirm this for any provider you consider; if a service needs the file itself, ask why.
What must you keep? Batched services give you a proof file that is the timestamp — lose it and the record is unrecoverable, because the chain holds a Merkle root rather than your hash. Direct-write services put the hash on-chain, so the certificate can be reconstructed from public data. See Merkle tree timestamping explained.
Is there a step you can forget? OpenTimestamps proofs are incomplete until upgraded after confirmation. This is the most common way people discover, years later, that they do not have what they thought.
Can someone verify it without the vendor? RFC 3161 tokens verify with openssl and the authority's certificate chain. A direct on-chain write verifies on any block explorer. A record verified through a vendor's portal depends on the vendor.
| Uploads file | Must keep artefact | Later step | Verify without vendor | |
|---|---|---|---|---|
| OpenTimestamps | No | Yes, the .ots file | Yes, upgrade | Yes |
| FreeTSA | No | Yes, the .tsr token | No | Yes, with the cert chain |
| ProofStamper | No | Yes, the token | No | Yes, with the cert chain |
| OriginStamp | No | Depends on plan | No | Partly |
| ScoreDetect | No | No | No | Through their platform |
| Bernstein | Encrypted client-side | No | No | Via their certificate |
| BlockchainSign | No | No | No | Yes, on Etherscan |
Where each one wins
OpenTimestamps — free, open, technically excellent, the developer default. Best if you are comfortable at a command line and reliable about files.
FreeTSA — free RFC 3161 infrastructure. Best for scripting timestamps into a build or archive.
ProofStamper — the same privacy model as ours, free, with a browser interface. If free matters and RFC 3161 suits you, this is a straightforward recommendation.
OriginStamp — years of operation, multi-chain, a real API. Best if you are integrating timestamping into a system at volume.
ScoreDetect — much cheaper per certificate at volume, plus WordPress, Zapier and an API. Best if you publish constantly and want protection wired into that pipeline.
Bernstein — pairs blockchain anchoring with a qualified eIDAS timestamp, which carries a legal presumption we cannot offer. Best if counsel has asked for one.
Us — one dedicated Ethereum transaction per certificate, payload readable as UTF-8 on Etherscan, no subscription, nothing to keep but the file. Best for a small number of confidential documents that matter, where a non-technical person may have to verify the result.
Where we lose
Worth stating without hedging: we are more expensive per certificate than ScoreDetect and infinitely more expensive than free. We have no API, no Zapier and no WordPress plugin. We are not a qualified trust service provider. If any of those is your deciding factor, buy elsewhere.
The questions to ask any provider
- Does my file leave my machine?
- What must I keep, and what happens if I lose it?
- Is there a step I have to remember later?
- Can someone verify this without your software or website?
- What happens to my records if you shut down?
Question five is not hypothetical. WIPO closed its own timestamping service in 2022, and the tokens survived only because they were independently verifiable artefacts rather than database rows.