Introduction
Relva ("we," "our," or "us") is committed to protecting your privacy. This Privacy Policy explains how BrowserKit, our native Safari content-blocking app for iOS and macOS, handles your information.
BrowserKit is designed with privacy as a core principle. Every step of filter-list compilation and rule matching runs locally on your device. Nothing is sent to our servers.
What We Do Not Collect
We want to be explicit about what BrowserKit does not do:
- We do not collect or transmit the URLs you visit
- We do not run analytics or telemetry of any kind
- We do not include a crash reporter that phones home
- We do not require account creation or authentication
- We do not share any data with third parties
- We do not build profiles or track behaviour across sessions
Network Requests BrowserKit Makes
BrowserKit makes exactly two kinds of outbound network requests:
- Filter list downloads. When you open the app or a background refresh fires, BrowserKit sends unauthenticated HTTP GET requests to the public URLs of the filter lists you have enabled (EasyList, EasyPrivacy, AdGuard, Peter Lowe's, URLhaus, Hagezi). No identifier of yours is included in these requests. The downloaded payloads are cached on-device in the shared App Group container.
- Nothing else. There are no analytics pings, no crash reports, no heartbeat calls, and no first-party telemetry of any kind.
How Safari Content Blocking Works
The Safari Content Blocker API is designed so that extensions cannot observe which pages you visit. BrowserKit compiles filter lists into a JSON rule file and hands it to Safari. Safari applies those rules in its own sandboxed process — your browsing URLs are never relayed back to BrowserKit.
The BrowserKit Toolbar Web Extension uses the activeTab permission to read the current tab's URL only when you click the toolbar button. That URL is passed to the native handler solely to normalize the hostname for allowlist membership. It is never stored beyond the in-memory operation, never transmitted, and never logged.
Data Stored On-Device
All data BrowserKit writes stays on your device, inside a sandboxed App Group container shared between the host app and its extensions:
- Compiled rule files — one JSON file per category blocker, read by Safari
- Cached filter list payloads — the raw text downloaded from public sources, used to rebuild rules
- Allowlist domains — hostnames you have chosen to trust, stored in the shared UserDefaults
- Scheduling state — the timestamp of the last refresh and the next scheduled refresh
None of this data leaves your device. Deleting BrowserKit removes the App Group container and all associated data.
Third-Party Filter Lists
BrowserKit downloads filter lists maintained by third parties:
- EasyList and EasyPrivacy (easylist.to)
- AdGuard filters (adguard.com)
- Peter Lowe's Ad & Tracking Server List (pgl.yoyo.org)
- URLhaus Malware Filter (urlhaus.abuse.ch)
- Hagezi DNS Blocklist (github.com/hagezi)
These are public, unauthenticated URLs. Your IP address is visible to the servers hosting these lists when BrowserKit fetches them, the same as any other HTTP request your device makes. We have no control over those servers' privacy practices.
Children's Privacy
BrowserKit does not knowingly collect any information from users under the age of 13. Because we collect no personal information from anyone, this applies universally.
Changes to This Policy
If we update this policy, we will post the revised version on this page with a new "Last updated" date. We encourage you to review this page periodically. Because BrowserKit collects no personal data, changes will typically reflect new features rather than new data practices.
Contact
If you have questions about this privacy policy or BrowserKit's data practices, please contact us:
Have more questions about BrowserKit?