Stylish is/was a very popular extension for the Chrome and Firefox web browsers, which let users add custom styles to certain websites. I was using it myself, until a helpful fellow told me it was apparently spyware; new owners decided to engage in data-slurping activities, which caused Google and Mozilla to pull the plugin from their stores.

However, since it's back in store, does that mean they've removed the malicious part of the code and it's safe to use again? I'm not really opposed against general data statistics gathering, I just don't like being uniquely identifiable.

I have read their privacy policy which states

We do not want to know your identity or any other personal information and we do not automatically collect data to try and figure out who you are

but stating is one thing, actually doing it is another.

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    I cannot tell you if it is safe again to use or not, but as an open source alternative, I would recommend using Stylus.
    – fgk
    Commented Dec 6, 2018 at 8:54

2 Answers 2


https://robertheaton.com/2018/07/02/stylish-browser-extension-steals-your-internet-history/ is the original technical write-up that covered the Stylish ordeal. There was a more recent one posted in August by the same author that covers the updated version of Stylish: https://robertheaton.com/2018/08/16/stylish-is-back-and-you-still-shouldnt-use-it/.

The latest write-up notes that Stylish added an opt-in screen when you install the extension.

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Personally, I think this snippet describes the author's stance on the update best:

Will SimilarWeb (the adtech company that owns Stylish) try to sneak in more underhanded tracking in the future? I don’t see why not. Can we trust them? In my opinion, no. [...]

It is also worth mentioning that the author recommends using an open-source variant called "Stylus".


You can block Stylish API in your hosts file and don't worry about it anymore. api.userstyles.org

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