A dynamic and lightweight censoring extension for Firefox. Censor matching phrases on web pages using rules you define, and omit websites that you want to see unfiltered. Curate the web how you want to see it.
- Censor words or phrases (plain text or regex), with optional case sensitivity
- Four censor modes, including substitute-phrase mode
- Omit specific URLs or whole domains
- Disable censoring at any time with a global toggle
- Manage censored phrases and omitted webpages directly in the extension popup
- Export and import your censor and omit lists to save and share with others
CensorCAT does not collect analytics, run accounts, or send your data to any server. Your censor list, omit list, and other settings stay on your device in Firefox’s local extension storage (browser.storage.local).
Censoring runs in the page in your browser; nothing is uploaded to the developers or third parties. Export/import only read or write files that you select.
Please open issues on this repository for bugs you encounter. Suggestions for enhancements are welcome.
This project is licensed under the MIT License. See the LICENSE file for details. By using this code, you agree that you are solely responsible for compliance with all applicable laws. I accept no liability for misuse or damages.
CensorCAT name, logo, and icon © TheWebCon / obviouslyweb 2026. The CensorCAT logo, name, and icon may be used in forked versions of this software with the clarification that such forks are not owned or maintained by TheWebCon / obviouslyweb. All other uses, commercial or personal, remain prohibited without explicit written permission.
If you are a fan of Justin Bieber, you're actually safe here. Just don't look at the legal disclaimers of my Woolwav project and you'll be fine.