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.
Certify a photo
Prove since when this photo has existed, exactly like this.
The condition of a flat, a car, a building site or a damage: protect the original photo and keep a proof of its date and integrity that anyone can check.
Certify a photo
We take you to the tool: you choose the photo and receive the certificate by email.
The photo you already have No app to install, and no need to take it again from somewhere else.
Public anchor The fingerprint is anchored in Polygon and in Bitcoin through OpenTimestamps.
Optional qualified timestamp You can add a qualified timestamp from the FNMT-RCM for €6.
Before you start
Three things worth knowing.
They decide whether this proof is useful to you, and they are better known now than later.
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.
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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.
How it works
From the photo to the certificate, in three steps.
From your phone or your computer, nothing to install.
- 01
Choose the photo
The original file, as it came out of the camera or the phone. 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. You receive the certificate and the verification package by email.
- 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.
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.
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.
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 changed since. If someone produces another version, the fingerprint will not match.
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 account, on the proof you choose. After that, €6 per timestamp.
If you need a legal presumption, add a qualified timestamp issued by the FNMT-RCM: the first one is free → Certify a photoFrequently 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, without taking them again in any app. Without an account, the photo is uploaded to generate the certificate and the verification package; 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 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.
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. Without an account the limit is 20 MB; with a free account, using Sellat Local, you can go up to 1 GB because the fingerprint is computed on your device.
Does it detect whether the photo was edited or is AI?
No, and be wary of anyone who promises that. What Sellat can read are the Content Credentials (C2PA) that some cameras and tools attach to the file: it shows what they declare, without verifying the device. You can do that reading for free in the credentials reader.
Does it help with a tenancy deposit claim?
It helps: it contributes photos with a date and an integrity that can be checked, which is exactly what tends to be missing. It does not decide who is right; whoever settles the dispute weighs that.
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 account, 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.
Certify a photo