Cookie statement

Since 9 October 2026, System1 Models operates under the name Decision Models (decisionmodels.io). References to System1 Models and system1models.ai in this document mean Decision Models and decisionmodels.io; nothing else changes.

Last updated: 7 October 2026

We use no tracking, advertising or analytics cookies, and our cookie-free page analytics stores nothing on your device, so we show no cookie banner.

Public website

The public pages of system1models.ai set no cookies, except one functional cookie when you choose the Peer-to-Peer or EU version of the site yourself. We count visits without cookies or other browser storage through our own Umami service (see section 2.2 of the Privacy Policy). The colour theme initially follows your operating system setting. We use browser storage for these display and language preferences:

Name	Purpose	Storage and duration
system1-theme	Saves light or dark mode when you use the theme switch	Local storage; retained for later visits until you clear this site's browser data
system1-lang	Saves your language choice when you use an EN/DE link or accept or dismiss a language suggestion, and suppresses further suggestions	Local storage; retained for later visits until you clear this site's browser data
system1-lang-suggested	Records that a language suggestion has been shown so it is not repeated in the same tab session	Session storage; the current tab's page session
s1m_region (cookie)	Remembers the site version (Peer-to-Peer or EU) you chose with the switch or a ?region= link. It is set only when you choose; automatic suggestions set nothing. Strictly necessary for the setting you requested (§ 25(2) no. 2 TDDDG)	First-party cookie; 1 year, or until you clear this site's browser data

These settings are not used for tracking. You can remove them by clearing this site's browser data. If browser storage is unavailable, the theme switch and manual language links still work, but your choices are not saved.

Dashboard (after sign-in)

The dashboard uses only cookies that are strictly necessary to provide the service you asked for (§ 25(2) no. 2 TDDDG). They do not require consent.

Name	Purpose	Duration	Set by
s1m_session (older sessions), s1m_session_*	Keeps you signed in using an opaque random token; versioned names allow secure session renewal	Authenticated session: up to 90 days, extended during active use (sliding expiry); an empty sign-out marker can remain for up to 90 days	api.system1models.ai
s1m_csrf	Protects forms against cross-site request forgery	Up to 90 days; renewed during active use	api.system1models.ai
s1m_oauth_state_google, s1m_oauth_material_google	Protect the Google sign-in against forgery (random state, PKCE verifier and nonce); sent only to the sign-in callback	10 minutes	api.system1models.ai

Each sign-in issues a fresh session ID (session rotation). You can end every active session on all devices and browsers with "Log out everywhere" in the dashboard; the normal "Sign out" button ends only the current session.

During renewal, your browser may briefly hold two session cookies. After sign-out, one empty cookie remains to prevent delayed responses from restoring an earlier login. It contains no authentication token and is cleared when you next sign in or when it expires.

All cookies are first-party, Secure, HttpOnly and SameSite=Lax.

Payments

When you top up, you are sent to a checkout page hosted by Stripe on stripe.com. Stripe sets its own cookies there, which are needed for fraud prevention and to complete the payment. See Stripe's cookie policy.

Sign-in with Google

When you sign in with Google, you are sent to Google's sign-in page, where Google's own cookies apply.

API and MCP

The API and MCP server do not use cookies. They authenticate with your API key.