Privacy Policy

Last updated: February 15, 2026

Overview

Sigil: 4chan is a Chrome extension that adds social features (voting, reputation, shill detection) to 4chan. We respect your privacy and process data locally whenever possible.

Data We Collect

• Google Account Email: Used for authentication via Google Sign-In (chrome.identity API). Your email identifies your account in Firebase.
• Sigil ID (username): A public username you choose, stored in Firebase and visible to other Sigil users.
• Votes and Claims: Your votes on 4chan posts and post claims are stored in Firebase Realtime Database, tied to your account.
• Direct Messages: Messages sent to other Sigil users are stored in Firebase, visible only to conversation participants.
• Shill Detection Data: Post fingerprints (text hashes, timing patterns) are stored locally in your browser's IndexedDB. This data never leaves your device.
• Extension Settings: Your preferences (NSFW filter sensitivity, radar threshold, etc.) are stored locally via chrome.storage.

Data We Do NOT Collect

• We do not track which pages you visit beyond 4chan.
• We do not collect passwords or financial information.
• We do not sell or share your data with third parties.
• We do not use analytics, tracking pixels, or advertising SDKs.
• We do not collect your IP address or location.

How Data Is Stored

• Firebase Realtime Database: Votes, claims, DMs, profiles, and reputation data are stored in Google Firebase, secured by authentication rules that ensure users can only modify their own data.
• Local Storage (IndexedDB): Shill detection fingerprints and persona data are stored entirely on your device and never transmitted.
• chrome.storage: Extension settings and preferences are stored locally.

AI Features

Sigil offers optional AI-powered thread summaries using Google Gemini. This feature requires you to provide your own API key (BYOK). Thread content is sent directly from your browser to Google's Gemini API. We never see or store your API key or the content sent to Gemini.

Data Deletion

Signing out of Sigil clears all local data from your browser. To delete your Firebase data (votes, claims, DMs), contact us at the email below.

Third-Party Services

• Google Firebase: Authentication and data storage. Firebase Privacy Policy
• Google Gemini API: Optional AI summaries (BYOK). Gemini Terms

Changes

We may update this policy. Changes will be posted on this page with an updated date.

Contact

Questions? Email us at instanthpi@gmail.com

← Back to home