Last updated: June 2026
This policy covers 0 Browser (the iOS app), the 0Cert web app at app.0cert.io, and the 0Cert Key Generation Center (KGC) at kgc.0cert.io. It explains what data is collected, what is not, and why.
Your private cryptographic keys are generated on your device and never transmitted anywhere, including to us. We do not track your browsing activity. We do not sell, rent, or share data with advertisers, because we don't have advertisers.
Identity registration. When you set up a 0Cert identity, you provide an email address or domain name. This is sent to the Key Generation Center (KGC) to issue a partial cryptographic key. The KGC stores:
The KGC does not store your private key, your user secret, or any data that would allow it to decrypt your traffic. This is a structural property of the Certificateless Public Key Cryptography (CL-PKC) protocol 0Cert uses, not a policy promise — the math is designed so the KGC cannot reconstruct your full private key even if it wanted to.
0 Browser does not log, track, or transmit your browsing history to us. When you visit a site, 0 Browser checks that site's DNS records and, if applicable, calls a public verification endpoint (/.well-known/0cert) hosted by that site itself — not by us — to confirm 0Cert support. This request goes directly to the site you're visiting, the same way your browser already requests that site's content.
Like virtually all web servers, kgc.0cert.io and app.0cert.io keep standard infrastructure logs (IP address, timestamp, request path) for security and debugging purposes. These logs are not used for tracking or profiling and are retained only as long as needed for operational purposes.
We do not share data with advertisers or data brokers. If you choose to register a website with 0Cert, your registered domain and the email you provide are visible to you and to the KGC operator (currently us, for the public KGC at kgc.0cert.io). Enterprises and developers may run their own private KGC instance, in which case this policy applies to data sent to their KGC, not ours — see github.com/0cert/kgc-server for self-hosting.
0Cert is not directed at children under 13 and we do not knowingly collect information from them.
0Cert's protocol, server, middleware, and iOS app source code are publicly available at github.com/0cert. You're welcome to audit exactly how data is handled rather than relying solely on this policy.
If this policy changes materially, we'll update the date at the top of this page. Continued use of 0 Browser or app.0cert.io after changes constitutes acceptance of the revised policy.
Questions about this policy or your data can be sent via our GitHub.