Prove this file existed, unchanged, at this time
— and let anyone check it without trusting us.
Your file never leaves your device. Only a fingerprint — a short unique code of the file — is sent to independent witnesses.
- Fingerprint
- Size
- Built-in credentials
Add a note (optional)
Where it came from, when you collected it, who collected it. Notes are saved with the receipt, but they are still your own words. Leave this blank for a simple receipt.
Independent witnesses, included automatically
- Bitcoin A public record that anyone can look up later. Confirmation usually finishes within a few hours.
- A timestamp authority An independent time record you can check right away.
- Public certificate logs Another public internet record, usually ready within about four hours.
How it works
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Drop your file
It is read only on your device. The file itself is never uploaded or stored.
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Get your receipt
Download a small receipt to keep with the original file — like a time-stamped ticket.
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Anyone can check it
They do not need an account, and they do not have to trust us. The receipt includes its own checker.
Who it is for
- Journalists Keep a dated copy of a photo, video, or document you collected.
- Photographers Show that an image existed, unchanged, on a given day.
- Small businesses Date contracts, invoices, or designs you may need to point back to.
- Artists Stamp a work-in-progress or finished piece without giving the file away.
- Insurance records Document damage or belongings so you can show when the photos were taken.
Common questions
Is my file uploaded?
No. Your file never leaves your device. LightDrawer only uses a fingerprint — a short unique code of that exact file — so witnesses can record that it existed.
What do I get?
A receipt you download and keep with the original file. It holds the time records and a checker page that works even without the internet.
How does someone check it?
They open the checker included in the receipt (or use Check a receipt on this site), drop in the receipt and the original file, and see whether the file still matches and when it was recorded.
Does it cost anything?
No. LightDrawer is free. If you would like to help keep it running, you can support it here.
What if LightDrawer disappears?
The receipt still works. It includes its own checker, and the time records live on independent public systems that do not depend on us.
Technical details
The fingerprint is a SHA-256 hash, computed in 4 MB chunks so large videos stay out of memory. The receipt is a ZIP containing statement.json (the fingerprint plus any notes), an OpenTimestamps Bitcoin proof, a FreeTSA RFC 3161 timestamp, a certificate-transparency proof, a plain-language cover page, and a copy of verify.html.
A receipt proves that a file with this fingerprint existed no later than the stamped times. It does not prove who made the file, that it is genuine or unedited before you stamped it, or that its content is true.
Optional notes follow Berkeley Protocol–style fields and remain the collector’s own statements. Built-in Content Credentials (C2PA) are read, not validated. Publishing to Sigstore Rekor is off by default because that log is public and permanent.
For a public web source, archive it yourself with perma.cc, the Wayback Machine, or Arweave, then paste that link in the notes.
A longer, precise walkthrough is in HOW-IT-WORKS on GitHub.