“My client's file shouldn't sit on a signing platform's server.”
Your clients sign together. COSigna never sees the document.
A Simple Electronic Signature under eIDAS. A qualified professional can add their own qualified signature.
Request alpha access →Invite-only during the alpha. The people who sign need no account.
How it works
11Create the ceremony. The file stays on your machine; COSigna receives only its fingerprint.
22Each party opens their link, confirms the document is identical, and adds their face to the previous COSignee's.
33You sign at your step with your own qualified signature. Everyone keeps the certificate.
Inside the ring or beside it? +
Inside (CASE-A): you are the COSignMaster (the organizer) or a COSignee and apply your QES at your step. Beside (CASE-B, Enterprise): you attach a qualified signature as a third-party attestor without joining the ring.Full legal brief →
Why it holds
The server is blind.
It never receives the document or a plaintext face, so privileged material is never shared with a platform.
What COSigna does not do
It does not verify identity: names are declared by the organizer. It is not a Qualified Trust Service Provider; the qualified element is you.
Request alpha access →Invite-only during the alpha. The people who sign need no account.
Report bugCOSigna — a Cryptographic Ring of Mutual Consent · The ring is strong because the loop is closed.The ring is strong because the loop is closed.COSigna
