Sellat is Now Available in ChatGPT: Protect Files and Create Verifiable Digital Proofs Through a Conversation
October 21, 2026
Sellat is now available in the ChatGPT plugin directory.
From now on, you can create proof of existence for your files, access their certificates, and request qualified eIDAS electronic timestamps directly from a conversation with ChatGPT.
It’s a new way to access the same digital proof infrastructure we provide through our website and API.
From a conversation to verifiable proof
Imagine you’ve just finished a contract, a design, or an important document.
You can open ChatGPT and simply type:
“I want to protect a file with Sellat.”
ChatGPT will open the Sellat panel, allowing you to select the file directly from your device.
Your browser calculates the file’s SHA-256 cryptographic fingerprint. Only this fingerprint and the filename are sent to Sellat. The original document never leaves your device during this process.
Sellat registers the proof and includes it in its blockchain anchoring system using Polygon and Bitcoin through OpenTimestamps.
The result is a verifiable proof of existence that you can later validate using open tools, without relying on Sellat.
Blockchain anchoring is performed in batches, so confirmation is not immediate.
Qualified eIDAS electronic timestamps
If you need evidence with specific legal recognition in the European Union, you can also request a qualified electronic timestamp issued by FNMT-RCM.
These timestamps comply with the eIDAS Regulation and benefit from a legal presumption of the accuracy of the date and time they indicate and the integrity of the data to which they are bound.
The qualified timestamp is optional and is only issued when you explicitly authorize it.
It does not replace an electronic signature or, by itself, establish the authorship of a document. Its purpose is to provide evidence of the existence and integrity of specific data at a particular point in time.
What can you do with Sellat in ChatGPT?
Beyond creating new proofs, the plugin lets you access previously registered proofs, check their anchoring status on Polygon and Bitcoin, and retrieve their certificates.
You can also check your account plan, see how many qualified timestamps you have available, and add an eIDAS timestamp to an existing proof.
To get started, you need to connect your Sellat account. Original file storage and payment management remain available through sellat.app.
One infrastructure, multiple ways to access it
Sellat was created to solve a specific problem: proving that a digital file already existed at a given date and has not been modified.
Today, this capability is available through our website, via API for businesses and developers, through integrations such as WooCommerce, and now directly within ChatGPT.
Our goal remains the same: to create independent, verifiable digital evidence that you can keep and validate over time.
What changes is how you access it.