Chrome and Firefox pull an extension called Stylish that sold to SimilarWeb in 2017, had roughly 2M users, and was found collecting users' web usage histories
The ‘Stylish’ extension has been removed after collecting users web-usage histories for over a year.
Context & Ripple Effects
Stylish, a styling extension with roughly 2M users, was acquired by analytics firm SimilarWeb in 2017 — and then spent over a year collecting its users' web-usage histories before Chrome and Firefox pulled it from their stores. The move repeats a script the stores already ran once: in 2016, Mozilla, Chrome, and Opera yanked the Web Of Trust add-on after it was caught selling browsing histories despite more than 140M downloads.
The pattern did not stop here. A year later, extensions with up to 4M installs were found leaking names and passwords to marketing intelligence service Nacho Analytics, and in 2020 Google removed 106 malicious Chrome extensions with 32M downloads that harvested browsing history and credentials. Stylish sits in the middle of that arc: a legitimate tool whose acquisition turned it into a data-collection asset.
First-order effects
- Roughly 2M Stylish users lose the extension outright, and SimilarWeb loses both a consumer distribution channel and the browsing-history feed the extension had been feeding it for over a year.
Second-order effects
- Chrome and Firefox now have a twice-proven template — Web Of Trust, then Stylish — for delisting popular extensions on privacy grounds, which raises review pressure on every analytics-backed extension still in the stores.
Third-order effects
- If the sequence holds — Stylish, then the Nacho Analytics leaks, then Google's removal of 106 harvesting extensions — extension marketplaces consolidate into de facto privacy regulators, and acquisitions of popular add-ons by data firms become the recurring risk vector they audit for.
The trend: Browser vendors are becoming the default privacy enforcement layer for extensions, repeatedly purging popular add-ons that monetize users' browsing histories.