1. What are cookies?
Cookies are small text files that a website stores on your browser when you visit it. They allow the site to remember information about your visit — for example, that you are signed in — so you do not need to re-authenticate on every page load. Cookies are a standard, widely-used feature of the web.
2. What cookies Tandem uses
Tandem uses only the cookies set by Better Auth, the authentication library that powers sign-in. These are strictly necessary authentication cookies. We do not use:
- Analytics cookies (no Google Analytics, Mixpanel, Plausible, or similar)
- Advertising or tracking cookies
- Third-party marketing cookies
- Performance or A/B testing cookies
Authentication cookies (Better Auth)
When you sign in to Tandem on the web, Better Auth sets a session cookie in your browser. This cookie holds an encrypted session token that identifies your authenticated session on the server. Without it, you would need to sign in again on every page visit.
These cookies are:
- Strictly necessary — the Service cannot function in an authenticated state without them. You cannot opt out of authentication cookies while remaining signed in.
- First-party — set by the Tandem domain, not by any third party
- Secure and HttpOnly — transmitted only over HTTPS and not accessible to JavaScript running on the page
- Session or persistent — a session cookie is deleted when you close your browser; a persistent cookie remains until it expires or you sign out
3. Mobile app: no cookies
The Tandem iOS and Android mobile apps do not use browser cookies. Instead, they store your authentication token in the device's local AsyncStorage. This is an on-device storage mechanism that is not shared with any other app or website. Clearing the app's local data or signing out will remove this token from your device.
4. Your controls
Because Tandem only uses strictly necessary authentication cookies, there is no opt-out from cookies while remaining signed in to the web app.
You can control cookies through your browser settings. Most browsers let you:
- View which cookies are set and delete individual cookies (this will sign you out of Tandem)
- Block cookies from specific sites
- Delete all cookies when you close your browser
- Set your browser to notify you before cookies are stored
If you delete or block the Tandem authentication cookie, you will be signed out and will need to sign in again the next time you visit. The Service will continue to work; you will just need to re-authenticate.
For instructions specific to your browser, refer to your browser's help documentation.
5. Changes to this policy
If we introduce new cookies — for example, if we add analytics or other optional features — we will update this Cookie Policy and the “Last updated” date before doing so. Material changes will be communicated via a notice in the Service or by email.
6. Contact
If you have questions about our use of cookies, contact us at info@our-tandem.com. For more information about how we handle your personal data more broadly, see our Privacy Policy.