Timestamp PDF

Add an RFC 3161 document timestamp to your PDF using a trusted Time Stamp Authority (TSA) server. Proves your document existed at a specific point in time. No certificate required.

Internet connection required

Timestamping requires contacting the selected TSA server to obtain a trusted timestamp token.

Click to select a file or drag and drop

PDF Documents

Your files never leave your device.

What Is a PDF Timestamp?

A timestamp proves that a particular document existed, unchanged, at a particular moment. The tool sends only a cryptographic fingerprint (a SHA digest) of your PDF to a Time Stamp Authority. The TSA signs that fingerprint together with the current time and returns a token, which is embedded in the file. Your document never leaves your device: the authority sees a 32-byte hash, not the contents.

This is defined by RFC 3161, the standard for trusted timestamps. Because the token is signed by a public authority, anyone can later verify when the document existed without trusting you, your computer clock, or this website. That is what makes it useful for contracts, invention disclosures, regulatory submissions and any situation where "this file is dated" is not good enough.

Unlike a digital signature, a timestamp needs no certificate, no key pair and no identity check. You are not claiming authorship - you are fixing a point in time.

When a timestamp is worth adding

  • Contracts and agreements: fix the moment a draft was finalised, before anyone sees it
  • Prior-art and invention records: dated evidence of what you had and when
  • Regulatory submissions: show a filing existed before a deadline
  • Invoices and quotes: prove terms were set on a given date
  • Creative work: establish when a design, manuscript or photograph was finished

Key Features

  • ✓ RFC 3161 compliant
  • ✓ No certificate needed
  • ✓ DigiCert-backed tokens
  • ✓ Verifiable in any reader
  • ✓ File never uploaded
  • ✓ No account, no limits

How to Add a Timestamp to a PDF

1

Upload the PDF

Select the file you want to timestamp. It is read locally; only a hash of it is sent to the authority.

2

Pick a timestamp server

The default server works directly from the browser. Traditional TSA endpoints are listed too but need a relay, and the tool says so.

3

Download the timestamped PDF

The token is embedded in the file. Open it in any PDF reader to inspect the timestamp and its certificate chain.

Getting a Verifiable Timestamp

Choosing a timestamp server

  • The default server accepts browser requests directly and returns DigiCert-signed tokens
  • Most legacy TSA endpoints do not send CORS headers and cannot be called from a web page
  • HTTP-only endpoints are refused outright by HTTPS pages, regardless of CORS
  • If you self-host, point the tool at your own relay to use any authority

Verifying the result

  • Open the timestamped PDF in a reader with a signature panel to see the token
  • The token covers the bytes as they were, so editing the file after timestamping invalidates it
  • Keep the timestamped copy exactly as downloaded - re-saving it can break the byte range
  • A timestamp proves time, not identity: it says nothing about who created the file

Frequently Asked Questions

No. Only a SHA-256 hash of the file is sent, and a hash cannot be turned back into the document. The PDF is read, hashed and rewritten entirely inside your browser.
No. Timestamping is separate from signing. The Time Stamp Authority signs a token over your document fingerprint, so you do not need a certificate, a private key, or proof of identity. If you also want to prove authorship, pair this with our digital signature tool.
A timestamp request is a cross-origin POST. The server has to reply with an Access-Control-Allow-Origin header or the browser throws the response away, and several long-standing TSA endpoints simply do not send one. Others are HTTP-only, which an HTTPS page refuses before the request even leaves. The default server handles both issues, and endpoints that need a relay are labelled in the list.
Open the file in a PDF reader that shows signatures - Adobe Acrobat, Preview, or a modern browser viewer. The timestamp appears as a signature whose certificate chain leads back to the authority. You can also inspect the embedded token with standard PDF tooling.
It appends a timestamp token in an incremental update, so the visible pages are untouched. Nothing is re-rendered and no quality is lost, but the file does grow slightly to hold the token and its certificate chain.
Yes, and it is the usual order of operations: sign the document first, then add a timestamp so the signature itself carries a trusted time. A timestamp added after signing also extends how long the signature stays verifiable, since it fixes the moment before the signing certificate could expire.
The token becomes invalid. A timestamp covers a specific byte range of a specific file; change one byte and verification fails, which is exactly the point. If you need a new version timestamped, timestamp the new file separately and keep both.
No. There is no account, no quota and no watermark. The only practical limits are your connection and whichever rate limits the timestamp authority applies to its public endpoint.

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