Where your data lives

Tostada has two modes. Which one you're in depends on how the app you're using was built, not on a setting you can flip mid-session.

Local mode — the default, and the one that never goes away

Run Tostada from the repo, or from the npm package, and everything stays in your browser:

• Your library — every token, family, principle, rule and override — under the tostada-library key in localStorage.
• Your undo stack and change history.
• Your Anthropic API key, if you set one (AI & BYOK).

There is no account, no server, and nothing to sign into. This is not a degraded free tier — it is the whole product, and the open-source build physically cannot contain the cloud code. Our own test suite runs against a build with no server configuration on every commit, which is what makes that a fact rather than a reassurance.

Back it up. localStorage is not durable storage: incognito wipes it on close, "clear site data" wipes it, and browser sync can clobber it across machines. Export your library as JSON regularly.

Cloud mode — app.tostada-ui.app

Sign in and your library lives in your organisation, so your team sees the same system. Three things are worth knowing.

Your device always has a current copy

Every save writes to your device first, then to the server. So when the network goes, the banner saying "changes kept on this device" is already true — it isn't a promise about what happens next. You can keep editing, and even reload the page and carry on from that copy; the next successful save reconciles it.

Your local library is never touched

The device copy lives under its own key. If you had a personal library in local mode and then signed into a team account, that personal library is exactly where you left it, and it comes back when you sign out.

Your first sign-in offers to copy it up into your team's library. Both answers leave the local one alone — "import" makes a copy, it doesn't move anything. You can also do it later from Settings → Local library.

If two people save at once, you're told

Tostada doesn't merge concurrent edits. What it does instead is notice: if someone saved while you were working, your save is held and you're shown who changed it and when, with two choices — load their version, or keep yours. The one thing it won't do is pick for you quietly.

What leaves your browser

Neither mode sends anything anywhere else. See Privacy for the AI side in detail.

Roles, and what they actually enforce

In an organisation, everyone has a role: reader, editor or admin. A reader gets the developer hand-off — copyable variables, the full export bundle — and cannot change the system.

That isn't just hidden buttons. Permissions are enforced by the database, so a reader's write is refused at the source whatever the browser does. The UI reflects the rule; it isn't the rule.

Getting your data out

Export as JSON, in both modes, always. That's the escape hatch, and it isn't going anywhere — if it ever did, the licence on the local build would let you fork the last version that had it.