Free Certified File Timestamp Online
ProofStamper is a free online tool that generates certified file timestamps using the RFC 3161 international standard. Drop any file in your browser — a cryptographic fingerprint is calculated locally, then certified by an independent Timestamp Authority. You receive a Proof Pack (PDF certificate + .tsr token) in under 30 seconds. No signup, no file upload, no installation. Available in 10 languages.
Whether you need to prove when a design was created, protect a piece of code, or document the date of a contract, a certified timestamp gives you independent, verifiable proof — and it doesn't have to cost anything. Here's how to create one for free, what it proves, and how it compares to paid alternatives.
How to timestamp a file for free in 3 steps
- Open ProofStamper: Go to proofstamper.com. No account to create, no software to install. It works in any modern browser, on desktop or mobile.
- Drop your file: Drag and drop any file — PDF, image, video, code, audio, archive. Your file is fingerprinted instantly using SHA-256, directly in your browser. The file itself is never uploaded anywhere.
- Download your Proof Pack: Click "Create proof." In a few seconds, you receive a Proof Pack containing a PDF certificate with the timestamp and file fingerprint, plus a .tsr token — the raw cryptographic proof, independently verifiable.
What makes a timestamp "certified"?
Not all timestamps are equal. The date on your computer, a screenshot, or an email timestamp can all be faked. A certified timestamp is different because it comes from a Timestamp Authority (TSA) — an independent server that:
- Verified date and time: Attaches a verified date and time from its own trusted clock, not yours.
- Digitally signed proof: Digitally signs the proof using cryptographic keys that cannot be forged.
- RFC 3161 standard: Follows the RFC 3161 standard — an international protocol specifically designed for trusted timestamping, used by governments and enterprises worldwide.
Because the timestamp comes from an independent third party using a recognized standard, it carries real evidentiary weight — unlike a file's "Date Modified" property, which anyone can change.
How ProofStamper compares to other timestamping methods
| Method | Cost | Speed | Independence | Privacy |
|---|---|---|---|---|
| ProofStamper (RFC 3161) | Free | 30 seconds | ✅ Independent TSA | ✅ Zero-knowledge |
| Blockchain timestamp | $1-10 | Minutes to hours | ✅ Decentralized | ⚠️ Hash may be public |
| Notary / lawyer | $50-200+ | Days to weeks | ✅ Trusted third party | ❌ Sees the document |
| Email to yourself | Free | Instant | ❌ Not independent | ❌ Easily faked |
| Cloud storage upload date | Free | Instant | ❌ Controlled by provider | ❌ Provider sees file |
| Soleau envelope (France) | €15 | 3-4 weeks | ✅ INPI | ❌ Mailed physical copy |
ProofStamper is the only method that combines all four qualities: free, instant, independently verified, and zero-knowledge (your file stays private).
Frequently asked questions
- Is there a limit to the number of free timestamps I can create?
- There's no hard limit on free timestamps. You can certify as many files as you need, one at a time. For batch processing (up to 50 files at once), you'll need the Pro plan.
- Does my file get uploaded to a server?
- No. Your file is fingerprinted using SHA-256 directly in your browser. Only the mathematical fingerprint is sent to the Timestamp Authority. ProofStamper never sees, stores, or has access to your file.
- What's a Proof Pack?
- A Proof Pack is a ZIP file containing your PDF certificate and the .tsr cryptographic token. Together, they form a complete, self-contained proof that your file existed at the certified date. Keep it safe — it's your evidence.
- Can I verify someone else's timestamp?
- Yes. Go to the verification page on ProofStamper, upload the Proof Pack (or the original file + .tsr token), and the tool will verify the cryptographic signature. You can also verify manually using OpenSSL.
- What happens if ProofStamper disappears?
- Your Proof Pack remains valid. The .tsr token is a standard RFC 3161 file that can be verified using open-source tools independently of ProofStamper. Your proof doesn't depend on us.
- How is this different from DocuSign?
- DocuSign is an e-signature tool — it proves someone agreed to something. ProofStamper proves a file existed at a date. They solve different problems. If you need proof of existence (not consent), ProofStamper is what you need.
- Why is it free?
- The Timestamp Authority (FreeTSA) is a free, community-operated service. ProofStamper generates revenue through its Pro plan and credit packs, which offer convenience features. The core timestamping function is free and will remain free.