Marc — Save to Arcos: Privacy Policy

Last updated: July 21, 2026

Marc is a browser extension that saves web pages, highlights, and notes into your Arcos account. This policy describes what data the extension handles and where it goes.

What Marc collects, and when

Marc only transmits data when you take an action — saving a page, creating a highlight or note, searching your library, or chatting about a saved page. The tools Marc draws on pages (the corner button, the highlight bar, the sidebar) send nothing until you use them.

• Account session — when you sign in, your Arcos session token is stored locally in the extension's storage. It is sent only to Arcos's backend to authenticate your requests.
• Pages you save — the page's address, title, and a copy of its content are sent to Arcos to create the item and its reader view in your account.
• Highlights, notes, and chats — text you highlight or write is stored in your Arcos account, governed by the privacy settings you choose there. Chat replies are generated by Arcos's servers using Anthropic's Claude as a processor; your chat messages and the saved page's text are sent for that purpose.
• Search queries — text you type into Marc's search (including the arc address-bar keyword) is sent to Arcos to search your own library.
• Settings — preferences (sidebar width, hidden sites, toggles) are stored locally in your browser and sync nowhere.

What Marc does not do

• No analytics, tracking, or advertising of any kind.
• No browsing-history collection — Marc reads the current tab only to show whether you've saved it, and page content leaves your browser only when you save or highlight.
• No sale or sharing of your data with third parties. The only processors are Arcos's own infrastructure (Supabase) and Anthropic (chat replies only).

Retention and deletion

Everything you save lives in your Arcos account and can be deleted there at any time (deleting an item removes it from search and chat context). Signing out of the extension deletes the locally stored session token. Local settings are removed when you uninstall the extension.

Contact

Questions or deletion requests: vincent@catalist.org.