The tenancy deposit
The condition of the flat the day you move in, and the day you move out. The most repeated dispute, and the easiest to avoid.
Certify photos and images
Certify a photo or image and prove since when it has existed.
Free, from your phone or computer, nothing to install. Choose the photo and receive a PDF certificate with its date and fingerprint, which anyone can check without asking us.
The date it certifies is today’s: the moment you protect the photo. If you want it to match the shot, take the photo with the camera from the tool itself and certify it on the spot.
Certify a photo for free
Choose the photo and receive the certificate and the verification package.
See a sample certificate (PDF) → Free Creating the proof and receiving the PDF certificate costs nothing.
Verifiable by anyone The date and the fingerprint are recorded in public networks: they are checked without relying on Sellat.
Optional qualified timestamp If you need a legal presumption, add a qualified (eIDAS) timestamp for €6.
How it works
From the photo to the certificate, in three steps.
From your phone or your computer, nothing to install. On a phone you can take the photo from the tool itself.
- 01
Choose the photo, or take it
The original file, as it came out of the camera or the phone. On a phone you can also take it from the tool and certify it on the spot. You can protect several at once.
- 02
Sellat creates the proof
It computes the SHA-256 fingerprint, records it and anchors it in public networks (Polygon and Bitcoin through OpenTimestamps). You receive the PDF certificate and the verification package.
- 03
Keep it and share it
If there is ever a dispute, you hand over the package: the other side can check it without asking us for anything.
If you send the photo through a messaging app before protecting it, protect the original you keep afterwards: that is the file the proof identifies.
When it is used
The day there is no dispute yet.
Useful photos are almost always taken before the problem, not after.
Handing over a vehicle
How the car was when you handed it over or picked it up, with its date.
The condition before building work
The wall, the floor or the façade before anyone comes in to work.
A damage, the day it appears
A leak, a dent, a crack: the photo is worth far more with a date that can be checked.
The product, before you ship it
How the order left your shop or your warehouse, for when a claim arrives about a broken part or a missing item.
Before you start
Three things worth knowing.
They decide whether this proof is useful to you, and they are better known now than later.
The date it proves is today’s
The proof records that the photo existed like this when you protected it, not when it was taken. That is why it pays to protect it the same day, not the day the problem appears.
WhatsApp changes the file
When you send it, the image is re-compressed and loses metadata: the copy that arrives is a different file with a different fingerprint. Protect the original, then send it.
If your camera signs, better still
Some phones and cameras attach Content Credentials (C2PA) to every photo. Sellat reads what those credentials declare and records it on the certificate; it does not verify the device or the process.
What about a screenshot? It is a file like any other and is certified the same way. Sealing it proves that this exact image existed on that date and has not changed since. It does not prove that what it shows is true: a conversation, a web page or a balance can be altered before the screenshot is taken.
Inside the package
This is exactly what you open two years later.
Not a promise and not a screenshot: the real list of files Sellat puts in your ZIP. What you see here is generated by the same module that builds the package.
Open the package Close the package
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original/<archivo>If the original is keptYour file, byte for byte
The exact photo you sealed, in a folder of its own so no other file in the package can be mistaken for it. It travels inside when the original is available: the upload that created the proof, or custody.
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certificado-<id>.pdfAlwaysThe readable certificate
The PDF you show a person or attach to a filing. It is an informative document: what actually gets checked is the file, not the PDF. If the file carried Content Credentials (C2PA), the certificate records them too — who signed, with which tool and whether they declare AI use — exactly as your browser read them when you protected it.
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proof.jsonOnce the batch is anchoredThe portable proof
Your file fingerprint, its Merkle leaf and inclusion path, the batch root and the public transaction that records it. This is the piece that lets anyone check everything without Sellat.
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sello-cualificado-<id>.tsrWith a qualified sealThe qualified seal
The RFC 3161 response from the qualified timestamping authority, exactly as it was issued. This is the file that fixes the date under eIDAS.
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autoridad-sellado.pemWith a qualified sealWho signed the seal
That authority signing certificate, with its SHA-256 written into the README. It travels inside so the check works offline and nobody has to go looking for it.
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anclaje-bitcoin.otsOnce the batch is anchoredThe Bitcoin anchor
The OpenTimestamps proof of the batch root. It may still be waiting for a block: it is a valid file and whoever receives it can upgrade it themselves.
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LEEME.txt / README.txtAlwaysThe instructions, in two languages
What each file is, what it proves and what it does not, and the exact commands to check it. In Spanish and English, so an expert or a lawyer never has to ask you anything.
It checks out without us and without the internet.
With the seal and the authority certificate inside the ZIP, the date is verified with standard tools on the machine of whoever receives it. If Sellat disappeared tomorrow, your package would still check out.
The package proves that this exact file existed on that date and has not been modified. It does not prove who created it, who took the photo, or what happened in front of the camera.
Scope
What it proves, and what it does not.
What it proves
That this exact image existed on the date of the proof and has not been modified since: if someone changes a single pixel, or produces another version, the fingerprint no longer matches.
What it does not prove
It does not say whether the photo was edited, whether an artificial intelligence generated it, who took it or where: the location, when present, is data the file itself declares. Nor does it prove when the shutter was pressed.
Price
Creating the proof costs nothing
Protecting a photo and receiving its certificate is free. The qualified timestamp is optional and is added from the certificate. Your first qualified timestamp is free. One per person, on the proof you choose. After that, €6 per timestamp.
If you need a legal presumption, add a qualified (eIDAS) timestamp: the first one is free → Certify a photo for freeFrequently asked questions
Before you ask.
Do I need to install an app to certify photos?
No. It is done from the browser on your phone or computer, with the photos you already have; on a phone you can also take the photo from the tool itself. With a free account, Sellat Local computes the fingerprint on your device and the original is not uploaded. If you also want a qualified timestamp, you ask for it in the same tool and a qualified trust service provider on the EU trusted list (currently the FNMT-RCM) issues it over the photo’s fingerprint.
Does it prove when the photo was taken?
No. It proves that the photo already existed, exactly like this, on the date you protected it. The time of capture is declared by the file itself in its metadata, and anyone can write that metadata; that is why the date that counts is the proof’s. If you take the photo from the tool and certify it on the spot, the two dates coincide for practical purposes.
Do certified photos have legal validity?
Electronic evidence cannot be dismissed just for being digital: article 41.1 of Regulation (EU) 910/2014 says so for an electronic timestamp, qualified or not. How much the evidence is worth is for the judge to assess in each case, like any other. If you need the legal presumption of date and integrity, add a qualified timestamp (art. 41.2): it is the only part you pay for.
Can I certify a photo I received on WhatsApp?
Yes, and what is recorded is that specific copy from today. Bear in mind that messaging apps re-compress images: the copy received is a different file from the original, with a different fingerprint.
Does it work for a video or an audio file?
Yes: it works for any file. With your free account, using Sellat Local, you can go up to 1 GB because the fingerprint is computed on your device and the file is not uploaded.
Does it certify that the image has not been manipulated?
It certifies that it has not changed since you protected it: any later edit, however small, changes the fingerprint and it no longer matches. What it cannot certify is what happened before: it does not detect retouching or AI-generated images, and be wary of anyone who promises that. What it does read are the Content Credentials (C2PA) some cameras attach to the file: it shows what they declare, without verifying the device.
How is it different from a certified photo capture app?
A certified capture app takes the photo inside the app and seals it at that moment, so the date of the proof matches the shot. Sellat certifies the photos you already have, taken with whatever camera you like: the date it proves is the moment you protect them. If you need both dates to match, take the photo from the tool or protect it right after taking it, from the same phone.
How much does certifying a photo cost?
Creating the proof and receiving the certificate costs nothing. The qualified timestamp is the only thing you pay for. Your first qualified timestamp is free. One per person, on the proof you choose. After that, €6 per timestamp.
The photo is already taken.
Protecting it today is what turns it into dated evidence. Free, and nothing to install.
Certify a photo for free