Who runs Cosignet

The founder

My name is Aliaksei Siuzeu (Alexei). I am a software engineer with 18 years of experience, based in Bialystok, Poland.

For the last 9+ years I have led development of an enterprise document-extraction platform for a Big Four consulting firm: OCR/ML processing of millions of tax document pages per year, with hard seasonal deadlines and sensitive financial data. I grew and led the engineering team from 5 to 20 people, and I designed and shipped LLM-based classification and validation in that production system.

Why Cosignet exists

AI agents stopped being autocomplete. They deploy, they move money, they delete data. Every integration guide says "add a human in the loop", and in practice that loop is a Slack button or a console prompt: a click that proves nothing about what exactly was approved, and that an injected prompt can talk its way past.

I wanted the approval itself to be evidence: a passkey signature bound to the exact payload, so that changing the amount, recipient, or command after approval breaks the approval. That is the whole product. I use it myself, in front of my own deploys and destructive scripts, every day.

How it is built

Cosignet runs on Cloudflare, uses standard WebAuthn passkeys (keys never leave the approver's device), and writes every approval to an append-only transparency log that anyone can verify independently. The verifiers are open source. The Security page lists what Cosignet guarantees and, just as importantly, what it does not.

What you can expect from me

• Honest limits. The non-guarantees section exists on purpose and will stay.
• Direct answers. Mail goes to me, not a queue: contact@cosignet.com.
• Careful changes. This product exists to prevent expensive mistakes; I treat its own changes the same way.

If you are evaluating Cosignet for anything serious, write me. I answer security questionnaires personally.

Links: LinkedIn, GitLab, contact@cosignet.com.