It is time to get rid of Stylish

Martin Brinkmann
Jul 3, 2018
Updated • Jul 3, 2018

The Stylish add-on and the linked repository for website styles changed ownership twice in the past years. The original owner sold Stylish back in October 2016 and the new owners of Stylish sold it again to the current owner SimilarWeb.

Stylish is a handy extension that you can use to apply custom CSS to websites. You may use it to change colors, remove elements, or add elements to sites to adjust them to your liking. You can remove advertisement, the comment section on YouTube, or turn Google Search's white background into something more eye pleasing.

Stylish collecting browsing data

The switch to the new owner of Stylish had massive privacy implications. SimilarWeb is known for its analytics offerings and it appears that the company collects browsing data from Stylish.

Users who install Stylish are automatically opted-in to sending anonymous data to Stylish. Stylish does include an option to opt-out of that in the extension options.

Back in 2017 we mentioned that it is unclear what data gets collected by the extension as it is not made clear in the privacy policy.

Robert Heaton analyzed Stylish's data collecting recently and discovered that the extension sends a user's complete browsing history back to Stylish servers. The data is linked to a unique identifier so that all of a user's browsing history can be linked together.

It is even worse for users who have an account on, a property owned by SimilarWeb, as Similarweb could link accounts to the browsing history.

Even if that is not the case, it is problematic even if SimilarWeb claims that it collects anonymized data only. One of the cases where this is problematic is when sites add information to the URL directly. Heaton mentions URLs that contain profile names, tokens, and URLs that use obscurity to protect data from third-parties.

Stylish makes a number of connections to whenever you connect to web resources. While you could think that this is done to return existing userstyles for these web resources, Stylish does transmit more information than it needs to for that functionality.

Heaton discovered that Stylish was transmitting obfuscated data to the userstyles address. He managed to decrypt it to find out that Stylish was submitting all browsing data to company servers. In other words, Stylish submits the full URL of any site you open in the browser the extension is installed in and Google search results as well.

SimilarWeb highlights what it collects in the extension's privacy policy:

From the Stylish desktop browser extension:

Standard web server log information (i.e., web request) as well as data sent in response to that request, such as URL used, Internet Protocol address (trimmed and hashed for anonymization), TabID, HTTP referrer, and user agent; and
Search engine results page data (keyword, order/index of results, links of results, title, description, and ads displayed).

From the Stylish mobile app:

Standard web server log information (i.e., web request) as well as data sent in response to that request, such as URL used, Internet Protocol address (trimmed and hashed for anonymization), HTTP referrer, and user agent;
Search engine results page data (keyword, order/index of results, links of results, title, description, and ads displayed);
Device ID (anonymized and/or de-identified using irreversible encryption and/or hashing);
Browser type, operating system and Mobile Network Code;
Device model name, device screen size and whether the device is rooted;
All web connections; and
Information regarding installed applications and their use (names, app IDs, versions of installed apps, installation and update dates, whether they are system apps, which apps are used, duration of use, whether the apps are on the home page);

If you use Stylish, at the very least disable the collecting of data in the extension settings.


We reviewed Stylus in 2017 which is a fork of Stylish that does not include the analytics component. You can install the extension and use it to load userstyles.

You may also use Chrome's overrides tool to make permanent changes directly to websites.

Now You: do you use Stylish?

It is time to get rid of Stylish
Article Name
It is time to get rid of Stylish
A new report suggests that the popular Stylish add-on for Google Chrome and Mozilla Firefox leaks all browsing data and more to the parent company.
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  1. ilev said on August 4, 2012 at 7:53 pm

    Doesn’t Windows 8 know that www. or http:// are passe ?

    1. Martin Brinkmann said on August 4, 2012 at 7:57 pm

      Well it is a bit difficulty to distinguish between domains and files for instance.

    2. Leonidas Burton said on September 4, 2023 at 4:51 am

      I know a service made by google that is similar to Google bookmarks.

  2. VioletMoon said on August 16, 2023 at 5:26 pm

    @Ashwin–Thankful you delighted my comment; who knows how many “gamers” would have disagreed!

  3. Karl said on August 17, 2023 at 10:36 pm


    The comments section under this very article (3 comments) is identical to the comments section found under the following article:

    Not sure what the issue is, but have seen this issue under some other articles recently but did not report it back then.

  4. Anonymous said on August 25, 2023 at 11:44 am

    Omg a badge!!!
    Some tangible reward lmao.

    It sucks that redditors are going to love the fuck out of it too.

  5. Scroogled said on August 25, 2023 at 10:57 pm

    With the cloud, there is no such thing as unlimited storage or privacy. Stop relying on these tech scums. Purchase your own hardware and develop your own solutions.

    1. lollmaoeven said on August 27, 2023 at 6:24 am

      This is a certified reddit cringe moment. Hilarious how the article’s author tries to dress it up like it’s anything more than a png for doing the reddit corporation’s moderation work for free (or for bribes from companies and political groups)

  6. El Duderino said on August 25, 2023 at 11:14 pm

    Almost al unlmited services have a real limit.

    And this comment is written on the dropbox article from August 25, 2023.

  7. John G. said on August 26, 2023 at 1:29 am

    First comment > @ilev said on August 4, 2012 at 7:53 pm

    For the God’s sake, fix the comments soon please! :[

  8. Kalmly said on August 26, 2023 at 4:42 pm

    Yes. Please. Fix the comments.

  9. Kim Schmidt said on September 3, 2023 at 3:42 pm

    With Google Chrome, it’s only been 1,500 for some time now.

    Anyone who wants to force me in such a way into buying something that I can get elsewhere for free will certainly never see a single dime from my side. I don’t even know how stupid their marketing department is to impose these limits on users instead of offering a valuable product to the paying faction. But they don’t. Even if you pay, you get something that is also available for free elsewhere.

    The algorithm has also become less and less savvy in terms of e.g. English/German translations. It used to be that the bot could sort of sense what you were trying to say and put it into different colloquialisms, which was even fun because it was like, “I know what you’re trying to say here, how about…” Now it’s in parts too stupid to translate the simplest sentences correctly, and the suggestions it makes are at times as moronic as those made by Google Translations.

    If this is a deep-learning AI that learns from users’ translations and the phrases they choose most often – which, by the way, is a valuable, moneys worthwhile contribution of every free user to this project: They invest their time and texts, thereby providing the necessary data for the AI to do the thing as nicely as they brag about it in the first place – alas, the more unprofessional users discovered the translator, the worse the language of this deep-learning bot has become, the greater the aggregate of linguistically illiterate users has become, and the worse the language of this deep-learning bot has become, as it now learns the drivel of every Tom, Dick and Harry out there, which is why I now get their Mickey Mouse language as suggestions: the inane language of people who can barely spell the alphabet, it seems.

    And as a thank you for our time and effort in helping them and their AI learn, they’ve lowered the limit from what was once 5,000 to now 1,500…? A big “fuck off” from here for that! Not a brass farthing from me for this attitude and behaviour, not in a hundred years.

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