Development

Topic	Replies	Views	Activity
Get started with Firefox extension development Extensions provide a simple and powerful way to personalize your browsing experience. If you know JavaScript, CSS, and HTML, you can build your own. If you are brand-new to add-on development, you can get started by che…	6	17104	September 30, 2025
About the Development category	0	4537	May 21, 2015
Questions about including third-party libraries	1	27	February 10, 2026
How does Mozilla calculate daily users in the statistics panel?	1	43	February 10, 2026
Is there a way to stream in-memory data into downloads.download? learning	0	16	February 9, 2026
Feedback wanted: Selenium WebExtension Bridge for Firefox feedback	0	20	February 8, 2026
Selection changed event behaviour changed since 148? issue	0	13	February 7, 2026
Proper way to create an add-on for internal use	1	19	February 6, 2026
Intercepting HTTP requests doesn't work	2	18	February 6, 2026
Adding onUserScriptConnect / onUserScriptMessage listeners	0	18	January 23, 2026
Is Firefox MV3 intentionally not supporting `browser.runtime.onMessage` in MV3 userScripts API? Why?	8	151	January 21, 2026
Why does runtime.onSuspend not execute window.localStorage.setItem? learning , issue	2	23	January 19, 2026
How to automate add-on option screen tests?	7	208	December 30, 2025
Firefox Default Themes & Theme Values	2	49	December 24, 2025
Insert text into textbox with add-on click learning	2	78	December 15, 2025
How to prevent redirecting to HTTPS when fetching local address from a background script?	2	37	December 3, 2025
Do older Firefox versions ignore "data_collection_permissions"?	2	209	December 3, 2025
A way to set tab context as default for new tab	3	91	November 18, 2025
[EDITED] Error: Permission denied to access property "then" issue , manifest-v3	4	2209	November 18, 2025
Funcions `loadOneTab` and `loadURI` in 2023 in Firefox Experimental API?	2	697	November 16, 2025
Foucs behavior issue on sidebar when opening	1	41	October 29, 2025
Pin Tab Enhancement / Side Bar Control	2	317	October 25, 2025
[Manifest V3] background script stopped when signed extension is up	3	76	October 15, 2025
WebExtension API support for web app windows	3	98	October 10, 2025
IDEA - Add Unsubscribe Footer thunderbird	0	37	October 5, 2025
Validation says data_collection_permissions missing, but exists in manifest? issue	2	1038	September 20, 2025
Do extension settings reference or depend on the extension's internal uuid?	2	29	September 19, 2025
Can we access location of new tab wallpaper?	2	50	September 15, 2025
License: This field, or custom_license, is required for listed versions	3	91	September 12, 2025
Error when use web-ext with chrome with `--keep-profile-changes`? issue	3	100	August 29, 2025

Get started with Firefox extension development

Extensions provide a simple and powerful way to personalize your browsing experience. If you know JavaScript, CSS, and HTML, you can build your own. If you are brand-new to add-on development, you can get started by che…