Transform Web Pages with CustomCSS Injector

CustomCSS Injector is a powerful Firefox extension designed for web developers and enthusiasts who wish to customize their browsing experience. This subscription-based tool allows users to write and apply custom CSS rules to any website effortlessly. With its intuitive interface, users can change colors, backgrounds, and even hide unwanted elements without needing to refresh the page. The extension supports applying CSS rules either to specific URLs, entire domains, or globally across all sites, providing flexibility in customization.

Additionally, CustomCSS Injector features a whitelist and blacklist option, enabling users to manage where their CSS modifications take effect. The built-in syntax highlighting and line numbering, powered by PrismJS, enhance code readability, making it easier to write and manage CSS rules. This tool is essential for anyone looking to personalize their web experience or test CSS changes in real-time.

App specs

  • License

    Subscription

  • Version

    1.3.2

  • Latest update

  • Platform

    firefox

  • Downloads

    1

  • Size

    44.31 KB

  • Developer

    • Blizz3

Program available in other languages



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Laws concerning the use of this software vary from country to country. We do not encourage or condone the use of this program if it is in violation of these laws.
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Is CustomCSS Injector safe?

100/100

Score result: Clean

This file passed a comprehensive security scan using VirusTotal technology. It is safe to download.

  • Virus free
  • Spyware free
  • Malware free
  • Verified by Security Partners

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Scan Info

Last scan
Wednesday, October 1, 2025
Scan provider
VirusTotal · Full report

File Integrity

File
1.3.2.xpi
SHA256
6d4eb57ecbfc0f49953e0e61a983bbe52a6f6d4fd07406cf45d55d6201098e0a
SHA1
19fd7aba3027710e63046ee4db2a351aa924e36e

Softonic security commitment

CustomCSS Injector has been thoroughly scanned by our advanced security systems and verified by industry-leading partners. This file comes from the official developer and has passed all our security checks, showing no signs of viruses, malware, or spyware.