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Mozilla Firefox vs Stylus

Mozilla Firefox logo

Mozilla Firefox

Technology

An independent web browser with its own rendering engine, funded almost entirely by search placement deals.

From
Free
Rated
-
Full reviewWebsite
Stylus logo

Stylus

Browser Extensions

Restyle the web with custom CSS

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Mozilla Firefox roughly 85 per cent of Mozilla's revenue comes from search default placement deals, overwhelmingly with Google, so the organisation that competes with Chrome depends on Chrome's owner for its funding and any renegotiation lands on Firefox's engineering budget within a quarter.; Stylus crashes and instability when applying certain styles
  • They diverge on capability: Mozilla Firefox covers Gecko engine, Stylus covers Custom CSS injection.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Mozilla Firefox and Stylus actually diverge.

Attributes where Mozilla Firefox and Stylus differ
AttributeMozilla FirefoxStylus
Pricing modelUnknownfree
PlatformsWindows, macOS, Linux, iOS, AndroidChrome, Firefox, Edge, Opera
CategoryTechnologyBrowser Extensions
Founded20042017

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Mozilla Firefox

  • Gecko engine
  • Full webRequest blocking
  • Total Cookie Protection
  • Container tabs
  • Extended Support Release
  • policies.json and ADMX
  • Built-in developer tools
  • Firefox Sync

Only in Stylus

  • Custom CSS injection
  • Style management
  • userstyles.world integration
  • Built-in editor
  • Chrome support
  • Firefox support
  • Edge support
  • Opera support

What people use each for

The jobs each tool is most often brought in to do.

Mozilla Firefox

  • Web development where you need to test against a non-Chromium engine before shipping, because Chromium-only testing hides real bugsnot Stylus
  • Users who require a full-strength content blocker, which Chrome's Manifest V3 no longer permitsnot Stylus
  • Managed fleets that need a browser on a slow release cadence with Group Policy control, using the ESR channelnot Stylus
  • Handling several accounts on the same service at once through container tabs, without separate profiles or private windowsnot Stylus

Stylus

  • Customizing website appearance with community-created CSS themesnot Mozilla Firefox
  • Writing personal style overrides for specific websitesnot Mozilla Firefox
  • Managing multiple styles across different websites automaticallynot Mozilla Firefox
  • Searching and installing user-styles for current websitesnot Mozilla Firefox
  • Migrating style collections from Stylish extensionnot Mozilla Firefox

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Mozilla Firefox

  • Roughly 85 per cent of Mozilla's revenue comes from search default placement deals, overwhelmingly with Google, so the organisation that competes with Chrome depends on Chrome's owner for its funding and any renegotiation lands on Firefox's engineering budget within a quarter.
  • Desktop market share sits at a few per cent, so commercial sites are tested against Chrome and Safari and a Firefox-only rendering or WebRTC bug is triaged as low priority by the site owner, leaving you with the workaround.
  • On iOS and iPadOS the browser is a WebKit shell required by Apple's rules, so it delivers the interface and Sync but none of the engine, extension or tracking-protection behaviour that make Firefox worth choosing on desktop.
  • Mozilla declines to implement several hardware-facing APIs on principle, including WebUSB, WebSerial, Web Bluetooth and WebHID, so a web application that talks to a device simply does not run and no configuration flag changes that.
  • Enterprise management is limited to policies.json and ADMX templates; there is no first-party equivalent of Chrome Browser Cloud Management, so fleet-wide reporting on versions and extensions requires third-party tooling you have to buy or build.
  • Mozilla repeatedly ships decisions its own user base objects to, such as enabling Privacy Preserving Attribution by default and the 2025 Terms of Use rewrite, and reversals arrive after the news cycle, so deploying it on a privacy argument means owning the communications work each time.

Stylus

  • Crashes and instability when applying certain styles
  • No visual element selector tool for identifying page elements to style
  • Security risk if downloading and applying untrusted user-created styles

Pricing, plan by plan

Mozilla Firefox

Free

No published plan breakdown. See the Mozilla Firefox review.

Stylus

Free
  • FreeFree
    • Custom CSS
    • Style library
    • Style editor

Which should you pick?

Choose Mozilla Firefox if

  • You need gecko engine.
  • You want to start without paying.
  • You work on Windows, macOS, Linux, iOS, Android.
  • You also want full webrequest blocking.
Mozilla Firefox review

Choose Stylus if

  • You need custom css injection.
  • You want to start without paying.
  • You work on Chrome, Firefox, Edge, Opera.
  • You also want style management.
Stylus review

Questions people ask

Is Mozilla Firefox or Stylus better?
Neither clearly leads. Mozilla Firefox starts at Free and Stylus at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Mozilla Firefox or Stylus?
Mozilla Firefox starts at Free and Stylus at Free.
Does Mozilla Firefox or Stylus run on more platforms?
Mozilla Firefox runs on Windows, macOS, Linux, iOS, Android. Stylus runs on Chrome, Firefox, Edge, Opera.
Can I use Mozilla Firefox for free?
Both have a free tier, so you can try either at no cost before committing.
What is Mozilla Firefox best used for?
Mozilla Firefox is most often used for web development where you need to test against a non-chromium engine before shipping, because chromium-only testing hides real bugs, users who require a full-strength content blocker, which chrome's manifest v3 no longer permits, managed fleets that need a browser on a slow release cadence with group policy control, using the esr channel, handling several accounts on the same service at once through container tabs, without separate profiles or private windows. Of those, web development where you need to test against a non-chromium engine before shipping, because chromium-only testing hides real bugs and users who require a full-strength content blocker, which chrome's manifest v3 no longer permits are not what Stylus is typically brought in for.
What can Mozilla Firefox do that Stylus cannot?
Mozilla Firefox covers Gecko engine, Full webRequest blocking, Total Cookie Protection, Container tabs. Stylus covers Custom CSS injection, Style management, userstyles.world integration, Built-in editor.

Answered from the vendors’ own pages

Mozilla Firefox: Does uBlock Origin still work on Firefox?

Yes. Firefox has kept the blocking webRequest API that Chrome removed with Manifest V3, so uBlock Origin runs with its full rule set rather than the cut-down Lite version Chrome requires.

Stylus: Is Stylus free?

Yes. Stylus is completely free and open-source, available for Chrome, Firefox, Edge, and Opera browsers.

Source
Mozilla Firefox: Is Firefox on iPhone the same browser?

No. Apple's platform rules require it to use WebKit, so on iOS and iPadOS you get Firefox's interface, Sync and bookmarks on top of Safari's engine. The privacy and extension behaviour are not the same.

Stylus: Can I use Stylus to change the browser UI?

No. Due to WebExtensions security restrictions, Stylus can only customize website pages, not the browser interface itself.

Source
Mozilla Firefox: How is Mozilla funded, and does that matter?

Mainly by payments for making a search engine the default, with Google as the dominant payer. It matters because it is a single-source dependency on a direct competitor, and it has been the subject of antitrust litigation whose outcome Mozilla does not control.

Stylus: What CSS pre-processors does Stylus support?

Stylus supports CSS, LESS, and Stylus syntax with built-in linting using Stylelint and CSSLint-mod with customizable rules.

Source
Mozilla Firefox: Can I manage it across a company fleet?

Yes, through policies.json or Windows Group Policy with the ADMX templates, and the ESR channel gives you a roughly yearly major version instead of four-weekly. There is no first-party cloud management console, so reporting needs other tooling.

Mozilla Firefox: Will every site work in it?

Most will. The exceptions cluster around sites tested only in Chrome, legacy enterprise applications, and anything using WebUSB, WebSerial, Web Bluetooth or WebHID, which Firefox does not implement at all.

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