Verifiable without trusting Sellat
Every proof can be checked with open tools and the public blockchain, without depending on sellat.app staying online. The verifier is open source.
About Sellat
Behind Sellat there is a simple question.
How do you prove that a file already existed, exactly as it is today, at a specific moment?
From a real claim to a product
Sellat was born from a real situation: an insurance claim where the adjuster asked for proof that a computer existed, in a specific state, on a specific date. There were invoices, photos and emails — but nothing independently proved when each thing existed.
That gap is not a rare case. Contracts, quotes, photographs of a property, creative work, system records: sooner or later someone needs to prove that exact data already existed at a given moment. And in a world where any image or document can be fabricated in seconds, the only thing that cannot be forged is the past.
Sellat turns that idea into something practical: verifiable proofs of existence and integrity, equally valid for a person with one file and for a system protecting thousands of fingerprints a day. The same engine at both ends.
Three principles we do not negotiate
The fingerprint, not the file
The proof engine works with the SHA-256 fingerprint. Creating a proof does not require handing over the original file.
Saying only what the proof demonstrates
A Sellat proof demonstrates existence and integrity at a point in time; not authorship or ownership. We would rather explain the limit than inflate the promise.
Who is behind it
Cristian Cascante
Founder
Full-stack engineer with more than fifteen years building web platforms, from custom WordPress to Docker infrastructure and AI-applied automation.
He designed and built Sellat end to end: the proof engine, the infrastructure and the product you are looking at.
Sellat is a Cristian Cascante Portabella product (Barcelona).
The best way to understand it is to use it
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