Mozilla Firefox

SEARCH & BROWSERS

LAST UPDATED 3 AUG 2026

OF 100

PARANOIA SCORE

WHAT THE POLICIES SAY

Mozilla Firefox is developed by the Mozilla Corporation, a wholly owned for-profit subsidiary of the nonprofit Mozilla Foundation, and its Firefox Privacy Notice states that browsing history and similar data are processed locally while "technical and settings data" is sent to Mozilla for core functionality. The privacy notice and Mozilla's own blog disclose that Firefox shares some data with advertising partners to support optional New Tab ads and sponsored search suggestions, and in 2025 Mozilla removed prior "we don't sell data" language from its Terms of Use and FAQ, attributing the change to varying legal definitions of "sale." Mozilla's track record includes a 2024–2025 episode in which it wound down, then took over a year to fully end, a bundled Firefox Monitor Plus partnership with a data-removal vendor whose CEO was reported to have founded people-search data-broker services.

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COLLECTION

The Firefox Privacy Notice states that Mozilla collects technical and settings data to provide core browser functionality, distinguish devices, and support default features.

mozilla.org ↗

COLLECTION

Mozilla support documentation states that Firefox collects technical and interaction (telemetry) data and sends it to Mozilla to understand feature usage, with a setting to turn this off.

support.mozilla.org ↗

OWNERSHIP TRANSPARENCY

Mozilla's own governance page discloses that Mozilla Corporation, which develops Firefox, is a wholly owned subsidiary of the nonprofit Mozilla Foundation.

mozilla.org ↗

[2022-09-13] · OWNERSHIP TRANSPARENCY

According to The Register, Google pays Mozilla hundreds of millions of dollars annually to be the default search engine in Firefox, a major revenue relationship not detailed in the Firefox privacy notice itself.

theregister.com ↗

SHARING

Mozilla support documentation states that, working with advertising partners, Mozilla may place sponsored shortcuts on the default Firefox home page and New Tab page.

support.mozilla.org ↗

[2025-03-03] · SHARING

The Register reported that Mozilla's 2025 Terms of Use and FAQ revision removed prior explicit language pledging that Mozilla does not sell users' data.

theregister.com ↗

[2025-09-02] · SHARING

Mozilla's own blog post explains that Firefox collects and shares some data with partners to support optional New Tab ads and sponsored search-bar suggestions.

blog.mozilla.org ↗

TRACK RECORD

Mozilla runs a funded Client Security Bug Bounty Program whose published scope expressly covers Firefox, Firefox for Android and Firefox for iOS, including Nightly, Beta and release builds, and which pays cash rewards between $3,000 and $20,000 (USD) for valid critical and high-severity client vulnerabilities.

mozilla.org ↗

TRACK RECORD

The general terms of Mozilla's Security Bug Bounty Program, which govern the Firefox client bounty, publish a safe-harbour commitment not to threaten or bring legal action against researchers who make a good-faith effort to comply with the program.

mozilla.org ↗

[2017-07-18] · TRACK RECORD

Mozilla commissioned and published a third-party security audit of Firefox Accounts, the central authentication service behind Firefox Sync and addons.mozilla.org, conducted by the firm Cure53 in autumn 2016 and released in July 2017; the audit identified 15 issues, none of which Mozilla states were exploited or put user data at risk. This is the only Firefox-tied published third-party audit located; it predates the current five-year window.

blog.mozilla.org ↗

[2024-03-22] · TRACK RECORD

In March 2024, Mozilla announced it was winding down its Onerep data-removal partnership bundled into Firefox Monitor Plus, after KrebsOnSecurity reported that Onerep's CEO had founded dozens of people-search networks.

krebsonsecurity.com ↗

[2024-12-31] · TRACK RECORD

Mozilla's transparency report for 1 July to 31 December 2024 publishes actual counts, including Firefox-specific breakdowns: 14 copyright takedown notices with 13 items removed from Firefox Add-ons, 43 trademark takedown notices to Firefox Add-ons with 38 items removed, and, across Mozilla services, 1 search warrant (1 produced), 23 subpoenas (7 produced) and 0 court orders.

mozilla.org ↗

[2025-02-13] · TRACK RECORD

In February 2025, KrebsOnSecurity reported that Mozilla was still promoting Onerep nearly a year after announcing it would wind down the partnership over the CEO's ties to people-search data brokers.

krebsonsecurity.com ↗

[2025-05-17] · TRACK RECORD

In May 2025, after two content-process exploits were demonstrated against Firefox at the Pwn2Own competition, Mozilla shipped fixed builds (Firefox 138.0.4, ESR 128.10.1, ESR 115.23.1 and Firefox for Android) within the same day of the second exploit announcement; Mozilla states neither attack escaped the Firefox sandbox, and that a year earlier it had patched an exploitable bug from the same event within 21 hours.

blog.mozilla.org ↗

[2025-11-20] · TRACK RECORD

In November 2025, Mozilla announced the Onerep-powered Monitor Plus data-removal service would be fully discontinued, with the wind-down period ending December 17, 2025.

krebsonsecurity.com ↗

TRACKING TECH

The Firefox Privacy Notice lists Total Cookie Protection among the default features Mozilla provides using collected technical and settings data.

mozilla.org ↗

TRACKING TECH

Mozilla support documentation describes Firefox's Enhanced Tracking Protection as blocking common trackers and harmful scripts to limit third-party data collection about browsing.

support.mozilla.org ↗

LAST REVIEWED 2026-08-03 · METHODOLOGY v1.7