It carries valid credentials
You will know who signed it, with which tool, which actions were recorded and whether the tool declared AI use. Valid means signed and unchanged since signing; it does not mean “real”.
C2PA reader
Check whether an image carries C2PA Content Credentials, and what they say.
C2PA is the open standard behind Content Credentials: a signed manifest, usually embedded in the image itself, that records how it was made and what was done to it. Drop a photo. Sellat reads its C2PA manifest in your browser — the image is not uploaded — and shows you who signed it, with which tool, whether it declares AI use and whether the content is still what was signed.
What the credentials tell you
Three possible answers.
Every image falls into one of these cases. None of them is a verdict on the photo: they are facts about what it carries inside.
It carries credentials that do not add up
The content no longer matches what was signed, or the signature cannot be validated. Something changed after signing, or the manifest is damaged.
It carries no credentials
The most common case. Either it never had any, or they were lost along the way. This is where the Sellat proof comes in.
Google Pixel 10 and C2PA: what its photos carry and how to check them →
Why they get lost
Credentials usually travel inside the file. And the file gets rewritten.
C2PA stores provenance in a signed manifest, normally embedded in the image itself. The standard also allows external manifests and markers that let them be recovered, but that is still uncommon: in practice, whatever rewrites the file usually takes the embedded manifest with it.
WhatsApp and social networks
WhatsApp recompresses every image sent the normal way: the copy that arrives on the other side is a different file, with no manifest. On social networks it depends on the platform — some already preserve and display credentials, others discard them.
Screenshots
A screenshot is a new image created by your device. It inherits nothing from the original.
Re-exporting or converting
Saving again, changing format or passing through an image-optimising service usually deletes the embedded manifest or invalidates it.
Read: what Content Credentials are and why they can disappear →
C2PA and Sellat
Two different layers. They need each other.
We do not compete with C2PA or with those who implement it. We answer a different question.
C2PA says where it comes from
Who signed it, with which tool, whether AI was involved, which edits. It lives inside the file, so it depends on nobody rewriting it along the way.
Sellat proves it existed like this, and when
A fingerprint of the exact file, publicly anchored. It lives outside the file, so no forward can erase it. Checking it needs that exact version: a screenshot or a recompressed copy is a different file, with a different fingerprint. That is why the Sellat ZIP keeps it in the "original" folder.
That is why they fit. Sellat reads the credentials today; preserving them inside the proof, before they evaporate, is the next step.
Who it is for
When a photo has to hold up as evidence.
Expert witnesses and surveyors
Photographs of damage, condition and measurements submitted months later. Knowing which credentials the photo carried when taken, and holding independent proof of when it existed.
Property managers
Check-ins, check-outs, incidents and works. A photo forwarded over WhatsApp carries nothing any more; the Sellat proof survives.
Law firms and insurers
Visual evidence that withstands a claim: which exact image, what it declared, and since when it has existed.
And if you are a creator who prefers a European proof layer independent of Adobe, the same tool serves you just as well.
When you protect a file
Available nowSellat reads your credentials and writes them on the certificate.
If you protect an image that carries Content Credentials, Sellat reads them in your browser and records on the certificate what they declared at that moment: who signed, with which tool and whether they declare AI use. It is what your file declared, read on your device; Sellat does not verify it and does not decide who made the file. It does not yet travel inside the portable proof anyone can re-check on their own: that step comes later.
Frequently asked questions
Before you ask.
What is C2PA?
An open content-provenance standard driven by the Coalition for Content Provenance and Authenticity (Adobe, Microsoft, Google, OpenAI, Leica and others). It embeds a signed manifest in the file recording how it was created and what was done to it. Its public name is Content Credentials.
Does Sellat upload my image to read it?
No. Reading happens in your browser with the standard’s open-source implementation. The image is not sent to any server and is not stored.
Does “valid credentials” mean the photo is authentic?
No. It means the signature is correct and the bytes have not changed since signing. It says who signed and what they declared; it does not say whether what the photo shows happened.
Can it tell whether an image was made with AI?
Only if the tool that generated it declared so in the manifest, as some image generators do. Without a declaration, Sellat does not know and does not guess.
Why does my phone photo carry no credentials?
Because almost no phone adds them yet. Some recent cameras and phones do, and compatible editors can add them on export. And even when present, the first forward over WhatsApp removes them.
What is the difference between C2PA and a Sellat proof?
C2PA describes the origin and lives inside the file. The Sellat proof shows that this exact file existed at a moment and lives outside it. The first can be lost on forwarding or conversion; the second cannot, because it is not inside the file. One caveat: checking the proof needs that exact version of the file, not a screenshot or a recompressed copy — which is why the Sellat ZIP keeps it.
Have the proof ready before you need it.
With or without credentials, the exact version of your image can be protected today.
Protect a file