Timestamp a file
How to timestamp a file: three steps, thirty seconds.
No jargon, no technical skills: here is how to timestamp a file, from capture to certificate, and how anyone can verify it.
Behind the scenes
What Proov-It does during those thirty seconds.
For those who want to understand the technology. Everyone else can skip it: it is all automatic.
SHA-256 file fingerprint
Proov-It computes the SHA-256 fingerprint of each file on your device, then recomputes it server-side. This fingerprint is unique: two different files, even by a single pixel, never share the same one.
RFC 3161 timestamp
The fingerprint is timestamped according to the RFC 3161 standard. The anchoring date and time are the ones that count.
Blockchain anchoring
The fingerprint and the timestamp are written to a public blockchain (opBNB network). Once written, this record can no longer be modified or deleted by anyone, not even Proov-It.
Certificate and third-party verification
A PDF certificate is generated with the fingerprint, date, geolocation and transaction identifier. A third party can recompute the file's fingerprint and compare it with the recorded one: if they match, the file is intact.
Upload or capture
Two levels of proof.
Uploading an existing file
You prove that this file, as is, existed on the date of submission and has not been modified since. Ideal for a contract, a quote, a creation, a document you received.
In-app capture (mobile)
The photo, video or audio is born inside the app, with its date and geolocation. Unlike an uploaded file, an image retrieved or generated elsewhere cannot be slipped in. Ideal for a property inspection, a job, a statement of facts.
Does it hold up in court?
In France, where Proov-It is based, evidence may be brought by any means unless the law requires a specific form of proof (Article 1358 of the French Civil Code). The EU eIDAS Regulation, which applies in every Member State, adds a non-discrimination principle: an electronic timestamp cannot be denied legal effect solely because it is not qualified (Article 41). In 2025, the Marseille judicial court (20 March 2025, RG 23/00046) relied on blockchain timestamps, recorded by a bailiff and supported by other evidence, to establish the prior existence of creations. It is a first-instance decision: it does not make a blockchain anchor sufficient evidence on its own.
A Proov-It certificate can be produced as evidence; the court assesses its weight. We attest to the anchoring date, the integrity of the file and, for a capture made in the app, the recorded geolocation, not the truth of its content.
Frequently asked questions
What people ask about timestamping.
Uploading a file or capturing in the app: what is the difference?
Uploading a file proves that it existed, as is, on the date of submission. In-app capture (on the mobile apps) goes further: the photo, video or audio is born inside the application, so a file retrieved or generated elsewhere cannot be submitted. This is the strongest proof.
What does the PDF proof certificate contain?
The anchoring date and time, the geolocation (for information), the SHA-256 fingerprint of the file, the blockchain transaction identifier and a verification link. Any change to the file breaks the fingerprint: integrity can be verified by a third party without going through Proov-It.
Does a timestamp prove that the content is true?
No, and no service can. Proov-It proves that a piece of content existed on a given date, in a given place, and has not been modified since. Whether what it shows is true is for the court or the expert to assess.
How many files can I put in one submission?
Up to 20 files of 100 MB each, photos or videos, in a single submission. That is nearly 1.5 hours of video in one proof.
Where are my files stored?
On secure servers located in France, with our hosting provider O2Switch. Files are encrypted server-side and kept for two years from the end of the plan you subscribed to (see our Terms).
Do I need technical skills to timestamp a file?
None. You choose a file or you capture, you add a comment, you submit. The certificate arrives within seconds. The blockchain works for you, without you having to understand it.
Who it is for
Built for anyone whose evidence may be challenged.
A date, a place, the condition of a property or the integrity of a file: as soon as it can be disputed, Proov-It freezes it.
Construction photo evidence
Electricians, plumbers, builders, drywallers, tilers, roofers: timestamped site photos, from the quote to the handover.
→02Proof of work completed
Call-outs, maintenance, repairs: before-and-after photos and time of visit, dated and geolocated.
→03Architects: site documentation
Site visits, minutes, snags, handover: a timestamped, geolocated project timeline.
→04Court experts and loss adjusters
Timestamped, geolocated, anchored inspection photos, with integrity the parties can check themselves.
→05Digital evidence for lawyers
Help your clients build dated evidence before litigation.
→06Service delivery proof and condition reports
Deliveries, move-in, move-out, cleaning, damage: dated and geolocated photos and videos.
→07Online proof for individuals
Neighbours, rentals, purchases, creations: prove the prior existence and integrity of any content.
→Keep reading
Related pages
Features
Photos and videos certified in the mobile app, frozen web pages, audio and documents: each file timestamped, anchored on a blockchain and verifiable.
Timestamp a file
Upload a document, photo or video and get timestamped proof of existence, anchored on a blockchain, in 30 seconds. No credit card needed.
Timestamp comparison
Non-qualified timestamp, qualified timestamp, report by a public officer: evidential weight, cost and use of each tool, to choose for each case.
Timestamped photo evidence
eIDAS Article 41, national rules of evidence, the court's assessment: what gives a photo weight as evidence, and how a timestamp makes it stronger.
Choose or capture
Documents, photos, videos. Or take a photo or video directly in the app.
Add the context
A comment, tags, a folder. To organise your proofs and find them easily.
Submit
You receive a PDF certificate attesting to the file's existence and integrity on the anchoring date and, for a capture made in the app, the geolocation recorded at that moment.