Why ProofStamper?
- Your files never leave your device — Only the SHA-256 fingerprint is sent to the certification authority. Zero upload, zero leak risk.
- Free, no sign-up required — Certify instantly, all formats accepted. No account needed.
How does it work?
- Drop your file: Drag and drop any file (PDF, image, ZIP, source code…)
- Automatic certification: Local SHA-256 hash + RFC 3161 timestamp via FreeTSA
- Download your proof: RFC 3161 token + readable PDF certificate
Who uses ProofStamper?
Integrity proofs for every profession
- Creators & Artists: Prove a version existed at a given date, without publishing your file.
- Freelancers & Contracts: Timestamp quotes, contracts and deliverables before sending to your client.
- Developers: Freeze a code version or binary with a timestamped proof.
- Photographers: Keep proof of the date of an original (RAW/JPG) before publishing.
- Students & Researchers: Date a thesis, paper or dataset at a precise version.
- Companies & Compliance: Timestamp meeting minutes, reports and internal audits before archiving.
ProofStamper vs cloud solutions
Two different approaches
| Criterion | ProofStamper | Traditional cloud solutions |
|---|---|---|
| Access | Free, no account | Account required, often paid |
| File processing | Local-first (browser) | Server upload |
| Verifiability | Verifiable by any independent expert | Depends on provider |
| Accepted formats | All (PDF, ZIP, images, code…) | Depends on provider |
Recognized proof, not a promise
RFC 3161 is an open international standard used in legal proceedings worldwide. Your proof can be verified independently of ProofStamper by any expert, lawyer or court — without depending on any service provider.
✓ International standard · Verifiable by any expert · Independent of ProofStamper
Legal notice
ProofStamper provides verifiable technical proof (integrity + RFC 3161 timestamp via FreeTSA). This tool does not constitute a qualified electronic signature under the eIDAS regulation (EU No 910/2014). For specific regulatory needs, verify applicable requirements.
Frequently asked questions
- How long does certification take?
- Under 30 seconds. The hash is computed locally, then timestamped via FreeTSA.
- Can my client verify the proof without an account?
- Yes. Verification is public and free — no registration required.
- What file types are accepted?
- All of them: PDF, images, ZIP, audio files, source code, spreadsheets…