Privacy

Last updated July 31, 2026

The short version

Proseidon stores your writing on your device — your computer for the desktop app, your browser's own storage for the web app. If you never create an account, none of your writing touches our servers. If you do create one, we store what's needed to back up and sync your library, and nothing else. We run no ads, no trackers, and no analytics inside the app, and we never train AI on your work.

If you use Proseidon without an account

Everything stays local. The web app keeps your projects in this browser's private storage; the desktop app keeps them in folders you choose. We cannot see them, and we hold nothing to delete — clearing your browser's site data or removing the app removes everything.

If you create an account

• Account details — your email address, a display name, and an avatar if you set one.
• Your synced library — the projects you back up: their text, structure, and media. Stored so your devices can stay in sync and your work survives a lost machine. It is your content; we access it only to operate the sync service.
• Device records — a name and identifier for each device you connect, so you can see and revoke them.

Accounts and synced data are hosted on Supabase, which processes this data on our behalf. Signing in sets one essential, HttpOnly cookie that keeps your session alive — it is not used for tracking, and there are no third-party cookies.

The website

This site serves static pages. When you click a download button we count the click (platform and version, nothing about you) so we know which builds people use. No advertising or cross-site tracking here either.

Deleting your data

Deleting a project in the app deletes it from sync. To delete your whole account and everything stored with it, contact us at deep@proseidon.io and we will remove it.

Changes

If this policy changes in a way that matters, we will say so on this page and, for account holders, by email.