Start Mozilla

Help us build the Web the world needs. Start hacking on Firefox.

[Start Mozilla @StartMozilla]

Our Firefox Nightly user base has _tripled_ this year. You've had a huge impact on how great Firefox 57 will be. Thank you all so much.

[Mike Conley (@[email protected]) @mike_conley]

I wrote a document about how I use Mercurial when hacking on Mozilla stuff, mainly targeted at new contributors:

https://t.co/1NRJmASAcy

[Firefox for Web Developers @FirefoxWebDevs]

🔐Unlock the world of #WebDev & #WebDesign
with our weekly @Mozilla Developer Newsletter.

📧 Sign up today for info on coding techniques & best practices, MDN updates, emerging technologies, developer tools tips, & more.

For more details, visit:
➡️https://t.co/koDRiWRxrl⬅️

[Start Mozilla @StartMozilla]

✨ Are you interested in improving theme management in Firefox? We would love your help with #goodfirstbug https://t.co/3YHPihUjP6 !

[Mozilla Festival @mozillafestival]

We know you’ve been preparing for this day all year...the call for #mozfest session proposals is officially open. We can’t wait to hear your ideas! https://t.co/53bIiYFk7i

[Mozilla @mozilla]

Please reply here if you are interested!
👇

[Firefox 🔥 @firefox]

We're rolling out a fix for the issues with add-ons right now! It will automatically be applied, so you don't need to take any steps to make add-ons work again & all your data should be unaffected.

Again, we're really sorry. More to come soon.

https://t.co/3xvV6RX22u

[Firefox DevTools @FirefoxDevTools]

Looking for a first simple bug to get started in open source? We make sure to always have some in @FirefoxDevTools!

This one is about adding a useful tooltip to our latest Flexbox tool!
https://t.co/GvRbaFh3ah

And @MicTig will happily help you get started on it!

[Mozilla Reps @mozillareps]

If you're feeling creative and up for a challenge, here's what you can do to help Mozilla spread the word about the Firefox Fight for You campaign. Learn more about how to participate here https://t.co/xLQsBz7qba #FFFY

[MDN Web Docs @MozDevNet]

Every week, we send a newsletter with updates to our MDN docs, @FirefoxDevTools tips, notable developer events, newest stories from @mozhacks, and news that's important to developers.

If you haven't subscribed, you're missing out:
https://t.co/owOa1cSQrM

[Mark Banner @Standard8]

Anyone looking to @StartMozilla with a #goodfirstbug on @Firefox code?

Help us enable @ESLint on more directories https://t.co/llGpNYuA5C

[Start Mozilla @StartMozilla]

Looking for a #goodfirstbug?

Help improve error messages for Firefox extension developers! https://t.co/s63pbYECm9

[Start Mozilla @StartMozilla]

If you're on OSX Mojave and using Nightly, are you seeing a black window and no text? We're looking for help reproducing this bug: https://t.co/KI8Ttj2Ps0

[David Walsh @davidwalshblog]

Want to learn about WebVR and what Mozilla's doing with it? Watch the live show today at 12PT!

https://t.co/pq8ni6cHK6

[Harald 🎤 @ Figma Config 2026 @digitarald]

Help @FirefoxDevTools

Naming things is hard, especially the different types of scripts in developer tools. Please RT & comment how you'd call A and B.

[Start Mozilla @StartMozilla]

Currently, extensions with empty default icons in their manifest produce a blank icon in the toolbar. Yuck!

You can help make sure that empty default icons aren't allowed by fixing this bug: https://t.co/QStBdjtjlo

[Start Mozilla @StartMozilla]

Looking for a good-first-bug to patch in Firefox? Try bug 1440700 and add frameID to the ontextMenus.OnClickData details object.

https://t.co/ss19eHwXYW

[Start Mozilla @StartMozilla]

Do you love using numeric keys as keyboard shortcut commands? We do, too!

Help us fix bug 1424708 in Firefox and bring shortcut power to the people!

https://t.co/BCz2s7vZdZ

[Start Mozilla @StartMozilla]

@marionpdaly We would be very interested in this!

[David Walsh @davidwalshblog]

CSS lovers: I need your help! An odd CSS bug in Firefox debugger!

There's even a solution included 😁

https://t.co/wzXCz12cXZ

[Start Mozilla @StartMozilla]

(Quick note for developers: if you're building @firefox on your own machine, you should run "mach bootstrap" soon - we have some new dependencies in the build process coming up, and that will make sure your system is up to date and ready.)