How to Prove a File Existed Before a Certain Date: Every Method Compared

To prove a file existed before a certain date, you need a record of that exact file that someone other than you created or holds, dated before the date in question. File dates on your own computer don’t count for much, because they can be changed. Below are the main methods people use (including Bitcoin timestamping with TimeBinder^®), what each one actually shows, what it costs, and when it is the right choice.

Disclosure: I’m Inna Hall, co-founder of TimeBinder, one of the tools compared here. I’ve tried to say plainly where another method is the better fit. This page is general information, not legal advice.

The two questions any method must answer

1. Is it this exact file? A record that says “a song called Demo 3” is weaker than one tied to the file’s bytes. A cryptographic hash such as SHA-256 ties a record to one exact file: change a single byte and the hash changes.

2. Who vouches for the date? If the only source of the date is you or your own device, it is easy to dispute. The more independent the source, the stronger the record.

Methods compared

Method	Tied to the exact file?	Who vouches for the date	Typical cost
File created/modified dates	No	Your own device	Free
Metadata inside the file (EXIF, document properties)	Partly	Whoever last saved the file	Free
Emailing it to yourself	If you keep the attachment as sent	Your email provider	Free
Cloud version history (Drive, Dropbox, Figma)	Yes, within the platform	The platform	Free to low
Git commit history	Yes, by commit ID	The committer (dates can be set freely)	Free
Posting a sealed envelope (“poor man’s copyright”)	Only if the envelope stays sealed	The postmark	Postage
Wayback Machine capture	Public pages only	Internet Archive	Free
Notary	Only what the notary records	The notary	Per appointment
US copyright registration	The deposit you submit	US Copyright Office	US$45–US$65 per application
RFC 3161 / eIDAS qualified timestamp	Yes (hash)	A Time Stamping Authority	Free to paid
OpenTimestamps	Yes (hash)	Public Bitcoin ledger	Free
TimeBinder	Yes (SHA-256 hash)	Public Bitcoin ledger	Free plan: 1 Token a month

Each method in brief

• File dates. Change when files are copied or synced, and can be set to anything. See can a file’s created date be changed?
• Emailing yourself. Better than nothing, but the record sits with your provider and copies can be edited. See emailing yourself as proof.
• Cloud version history. Strong for everyday work, but the account and its history belong to the platform and can be lost.
• Git. Great for showing order and integrity, weak on dates. See are Git commit dates proof?
• Poor man’s copyright. A postmark dates the envelope, not necessarily what’s inside. See a better alternative to poor man’s copyright.
• Wayback Machine. Good independent evidence for public web pages; no help for private files. See is the Wayback Machine proof?
• Notary. A notary confirms identity and signatures on a date; most don’t examine or fingerprint digital files. See blockchain timestamp vs notary.
• US copyright registration. The step that unlocks lawsuits and statutory damages in the US. Not a way to date every draft. See copyright registration vs a timestamp.
• RFC 3161 and eIDAS qualified timestamps. Precise and, in the EU, legally presumed accurate when qualified. See RFC 3161 vs blockchain timestamps.
• OpenTimestamps. Free, open source, Bitcoin-anchored, command-line focused. See TimeBinder vs OpenTimestamps.
• TimeBinder. A web app: files are hashed in your browser and never uploaded, the fingerprint is anchored to Bitcoin, and you get a Proof of Time Certificate that others can use to verify the file. It shows the file existed no later than the anchor time and still matches its fingerprint.

Which to use when

• Songs, manuscripts, designs and code you’re about to share: a hash-based timestamp before you send it, plus the email or upload you send it with. Guides: music, manuscripts, designs, source code.
• US works you may need to enforce: register with the Copyright Office as well.
• EU contracts and regulated records: consider a qualified timestamp from an EU trust service provider, alone or alongside a blockchain anchor.
• Inventions: dated records support, but don’t replace, a patent filing. See prove you invented something first.
• Public web pages: Wayback Machine capture plus your own timestamped copy.

A simple routine

1. Decide which moments matter: first draft, each version you share, final release.

2. At each moment, keep an untouched copy of the files and timestamp them. On TimeBinder one TimeBind covers up to 10 files; the free plan includes 1 Token a month, and Essential (US$20/month, 5 Tokens) or Expert (US$50/month, 15 Tokens) cover more. See pricing.

3. Store the certificate with the files and a second copy elsewhere. Keep your emails, version history and contracts too: the strongest case uses several independent records that agree.

No method on this list proves who created a file. A timestamp gives verifiable evidence of when a file existed; authorship and ownership are shown by your drafts, contracts and the people involved.

Guides by file type

Every format stores different dates, and some store none. These guides cover what each one records and what to freeze:

• Word documents and Scrivener projects
• PDFs: contracts, proposals and whitepapers
• Manuscripts before submitting
• Screenplays
• Source code
• Jupyter notebooks and research results
• RAW photos
• Photoshop (PSD) files
• Procreate illustrations
• Figma and Sketch designs
• CAD and BIM models
• 3D models (STL and 3MF)
• Video edits (Premiere, Final Cut, Resolve)
• Ableton projects
• WAV stems and bounces
• What happens to file dates when you copy, zip or download
• Date created vs date modified vs date taken

Unfamiliar terms are explained in the glossary of timestamping terms. For more step-by-step articles, browse all our timestamping guides.

Plan details were checked against timebinder.io/pricing on 29 October 2026.