Privacy policy

Effective October 2, 2026 · Operated by System2 · Contact: previbe.ai@gmail.com

System2 is a Chrome extension that decides which of your chosen topics the current page belongs to and shows a reminder. This policy explains what data the System2 extension and the System2 service handle, why, where it is kept and how you can delete it.

What the extension reads in your browser

Auto-analysis is off after installation. Only when you create topics and turn it on does the extension ask Chrome for permission to read websites. It then reads the current page when you open a new page or a single-page app changes its address. It does not keep watching scrolling, comments or video playback. It does not run in incognito windows. Turning auto-analysis off stops further reading, though a request already sent cannot be recalled.

Search results, feeds, directory pages, sign-in and payment pages, and known sensitive sites are skipped. Before extracting text the extension checks for password, card and verification-code fields; forms, inputs, editable areas, scripts and hidden elements are left out. These rules cannot recognize every piece of sensitive ordinary text, so you can add any site you do not want analyzed to “Excluded addresses”.

Bilibili video pages: instead of reading the page, the extension asks Bilibili for the video’s details, tags and subtitles, the same way Bilibili’s own player does. These requests go to Bilibili, and your browser attaches your Bilibili cookies under Bilibili’s rules. The extension does not read or store those cookies and never sends them to the System2 service.

YouTube video pages: the extension asks YouTube for the video’s public details and transcript. These requests carry no YouTube cookies; they include the video ID and your browser language (to pick the subtitle language).

What is sent for analysis

For each analyzed page, the extension sends the System2 service:

• an anonymous installation credential, the service mode, the extension version and a request ID;
• the page’s domain, title, description, author, publish time, language and headings;
• the main text trimmed to at most 18,000 characters. For videos this is the category, tags and subtitles; for X and Reddit posts it is the post itself, without replies or comments;
• the names and definitions of up to 20 enabled topics;
• if you use your own key: your TypeSafe API key, in an HTTPS request header.

The extension does not send the full URL, page source, cookies, passwords, form contents, page scripts or your browsing history.

Who receives this data

• The System2 service, hosted on Vercel in Tokyo, Japan. It receives the request, passes it to the model and returns the result to the extension.
• The model provider. On the free trial, requests go through Vercel AI Gateway to TypeSafe (the Jev model). With your own key, the System2 service calls TypeSafe directly using your key. The provider handles request content under its own privacy policy.
• Supabase, System2’s database in Tokyo, Japan, which keeps only the anonymous records listed below.
• Bilibili and YouTube, contacted directly by the extension for subtitles only when you open their video pages (see above).

We do not share data with anyone else.

Where data is kept and for how long

In your browser

• Topics, excluded addresses, settings, the anonymous installation credential and the optional API key are kept in the extension’s local storage (chrome.storage.local), without Chrome sync. This is not your operating system’s keychain; web pages cannot read it.
• Results and your manual labels for up to 500 pages. Entries are keyed by a SHA-256 digest of the URL and contain no page text or full URL. Automatic results expire after 24 hours; manual labels stay until you clear them.
• The current tab’s analysis state and URL are kept in session storage and cleared when the browser closes.
• With “Show what the model saw” turned on (off by default), the text sent to the model stays only in the open page’s memory and is gone when the page is reloaded or closed.

On the System2 service

• An HMAC digest of the installation credential and the installation ID, until you use “Confirm deletion of all data” in the extension, which revokes the credential. Uninstalling cannot notify the server, so the record stays, but it is not linked to any page content or personal identity.
• Free-trial counts, request IDs, input token counts and billing settlement records, used for billing, preventing double charges and reconciliation. These currently have no automatic deletion period and contain no page content, URLs or topics.
• Abuse-prevention signals: digests of IP addresses keyed with a secret that changes daily. Raw IP addresses are not stored, and the digests are deleted after 48 hours.
• Corrections uploaded by older versions: deleted after 90 days, or when you delete all data. The current version no longer uploads them.
• Page text, full URLs, topic definitions and API keys are not written to the database or application logs.
• Vercel’s own access and runtime logs may include IP addresses and are kept under Vercel’s policies.

Your choices

• Turn auto-analysis off at any time, or add sites to “Excluded addresses”.
• In settings, delete your API key, delete or disable topics, and clear the cache and manual labels.
• Deleting all data turns analysis off, clears local data and asks the server to revoke the installation credential and delete feedback. Billing records are not deleted.
• For questions or deletion requests, email previbe.ai@gmail.com.

What we do not do

Data is used only to decide which topics a page belongs to. It is not used for advertising, sold, used for credit decisions or to infer personal traits, or passed to anyone for an unrelated purpose. System2’s use of information received from Chrome extension APIs adheres to the Chrome Web Store User Data Policy, including the Limited Use requirements.

Changes

When this policy changes, the effective date above changes too. Significant changes to how data is used will be noted in the extension’s release notes.