When you sign in, we receive your Twitch account information (display name and avatar) via OAuth. We do not store your password or any Twitch credentials directly.
When you first sign in, we also save which site or link first brought you to UltraKaizo (for example a Reddit post), and your answer if you tell us how you found us. We use this only to learn where players come from.
Your game ROM is stored in your browser's IndexedDB. Save states are stored locally on your device. None of this data is uploaded to our servers unless you explicitly use co-op features, in which case save data may be temporarily stored server-side to enable session resumption.
On your first visit we note in local storage which site or link brought you here. It stays in your browser unless you sign in.
We use a session cookie for authentication via Supabase. We do not use tracking cookies, analytics cookies, or any third-party cookies.
We use Supabase for authentication and Vercel for hosting. Both services have their own privacy policies. We do not share your data with any other third parties.
Your account data is persisted for as long as your account exists. You can permanently delete your account at any time from the Settings tab of your profile: your personal data is erased immediately and irreversibly, and shared co-op run history is anonymized. Game data (ROM, save states) is local to your browser and is not retained by us. Co-op session data is temporary and deleted after the session ends.
For questions about this privacy policy or your data, reach out via GitHub issues on the UltraKaizo repository.
Last updated: July 11, 2026