Privacy

Last updated September 22, 2026

Without an account

The desktop app keeps your projects in folders you pick. The web app keeps them in your browser's storage. Your writing never reaches us. The web app does send us error reports and a visit count, described further down. The desktop app sends neither.

With an account

When you create an account we store:

• Your email address, display name, and handle and avatar if you set them. Avatars are stored at a public link, so anyone with that link can see the picture.
• Your plan, the date you accepted the terms, and when you last signed in.
• The projects you sync: text, folders, images and other media, version history, comments, and a search index made from your text so search works on every device.
• For each device you connect: its name (the name your computer has on the network), its operating system, the app version, and when it last synced. You can see and remove devices in the app.
• If you invite someone to a project, their email address, so the invite can reach them.

We only open your synced projects to run the sync service or to fix a problem you ask us to look at.

Signing in with Google

If you sign in with Google, Google gives us your name, email address and profile picture. That is all we ask for. We can't see your Gmail, Drive, contacts or anything else in your Google account. We use your email address to find or create your Proseidon account, and your name as your display name. We don't sell or share this information, and we don't use it for ads. You can remove Proseidon's access at any time from your Google account settings, under Security, "Your connections to third-party apps and services".

Publishing and beta readers

When you publish a piece, we store the published text, its description, your author name and, if you set one, the password (stored in a form that can't be read back). If you leave notes on a password-protected piece as a reader, we store the name you typed, your notes and the passage you highlighted, so the author can read them.

What the web app sends us

These are sent whether or not you have an account.

• Error reports. When the web app hits an error, it sends us the error message, where in the code it happened, the last few dozen lines of the app's own log, the app version, your browser type and the page path. The report is not linked to your account. It can contain a project or file name if one appeared in the log.
• Visit count. Each time the web app opens it records the page, the app version and your browser type, plus a code made from your IP address, browser and the date. The code changes every day and can't be turned back into your IP address. We use it to count visitors per day. We don't store IP addresses.

There is no setting to turn these off yet.

This website

• When you click a download button we store the date, the file and version, your operating system and browser type, the page you came from, and your country. No IP address.
• We count page views without cookies.

Cookies

On app.proseidon.io, one cookie keeps you signed in (for up to a year) and a second one lasts ten minutes while you confirm a new account. On proseidon.io, opening a password-protected piece sets a cookie that remembers the password for 30 days. That's all. No advertising or tracking cookies.

What we don't do

We don't sell data and we don't show ads. Proseidon has no AI features. Your writing is never sent to an AI service or used to train one.

Why we're allowed to

We process your account and synced projects because you asked us to: without them, sync can't work. We collect error reports, visit counts and download counts because we have a legitimate interest in finding bugs and knowing how many people use Proseidon. That interest never overrides your rights.

How long we keep things

• Account details and synced projects: until you delete them or your account.
• A synced project you delete: kept for 30 days so you can change your mind, then removed.
• We also keep daily backups of the database for a short time, so deleted data can stay in a backup for a few days after it's removed.
• Error reports, visit counts and download counts: we don't delete these automatically yet.

Your rights

You can ask for a copy of your data, ask us to correct it, or ask us to delete it. "Download my library" in the app gives you a zip of all your projects at any time. To delete your account and everything stored with it, email deep@proseidon.io. We will do it within a month. If you live in the EU or UK, you can also complain to your country's data protection authority.

Changes

If we change this policy in a way that matters, we'll update this page, and we'll email account holders.