About Signunder
Signunder exists because of a gap that is structural rather than technical. EU law requires AI-generated content to be marked. Signing it is a solved problem — there is a good open-source implementation and a free watermark. What is not solved is doing it in your own name: a certificate can only be issued to a product that is itself on the C2PA conforming-products list, so every hosted signing service signs as itself, and none of them will take you through your own listing.
So a company shipping generation under its own brand, on open models or across several providers, has three options: appear in a supplier’s name, do weeks of unfamiliar paperwork, or wait. Signunder is the fourth.
Where this has got to
Signunder is pre-launch and built by one person in Ireland. Our own C2PA conformance application is the first thing underway, because taking customers through a process we have not been through ourselves would be absurd. We are also talking to companies shipping AI generation to test whether this is worth building at all — if the answer is no, we would rather find out in October than sell something nobody needed.
That is also why there is nothing to buy on this site yet, and no customer logos or testimonials: there are no customers yet, and inventing them is exactly the kind of unverifiable claim this product exists to prevent.
How we work
Your name, your key, your record
We never hold a customer’s private key in software, and we would rather take you through your own conformance than sign on your behalf. A provenance record that names your supplier instead of you is not worth much.
Every claim carries its source
Everything we assert about the regulation, the platforms and the competition was read from a primary source, and we record the date we read it. Where we are unsure, we say so instead of rounding up.
We measure rather than relay
Watermark robustness and what survives an upload to each platform are things we test ourselves and publish, monthly. Vendors’ claims about their own marks are not evidence.
The core is open
Signing, watermarking and fingerprinting are published as open-source libraries. If you would rather run it yourself, you should be able to, and you should be able to read what we do to your files.
Be marking by 2 December
Signunder is being built now, in the open. Leave your email and we will tell you when the free checker and the signing API are live, and nothing else.
One address, used only to tell you when Signunder is ready. No newsletter, no sharing with anyone.