The Extension Zone team had the opportunity to interview Jorge Villalobos; add-on developer relations lead at Mozilla (and a very nice dude in general).

How to get your extension featured? Which technology should you use to build your add-on? In which category you’ll gain more traction?
Read this interesting interview and you’ll find some very useful information, statistics, insights and personal recommendations, from the guy who calls the shots in the Firefox add-ons community.


Let’s start with a short bio. Tell us about yourself and your position in Mozilla.
I was born and raised in Costa Rica and have always had an interest in computers and coding. I studied Computer Science in the University of Costa Rica and then completed my Masters in Computer Science at Syracuse University in upstate New York.

After finishing grad school I joined Glaxstar (now named Appcoast), a company then completely dedicated to Firefox add-on development. After years of contributing to the add-ons ecosystem, both professionally and as a volunteer, I joined Mozilla as Add-ons Developer Relations Lead. While I still hold the same position, my role has expanded into other areas as needed. I also co-founded the Mozilla Costa Rica volunteer community.

Interesting statistics to share?
We have reached various interesting milestones on AMO recently. We surpassed 4 billion add-on downloads and our most popular add-on, AdBlock Plus, has been downloaded over 300 million times and reached 20 million active users in December.

We perform code reviews for all add-ons and add-on updates submitted to AMO. This task is partially handled by a volunteer team of experienced add-on developers. We review about 1400 add-ons per month, with about half of them being handled by the volunteer team.

What do you look at when you search for an add-on to present in the Featured section.
Anyone can nominate add-ons to feature, though it’s usually the developers who self-nominate. We have a Featured Add-ons Board composed of community members who help us look at the candidates and pick a new set for every month. We don’t rotate add-ons out of the featured list as often, though, since we like having many great recommendations for our users.

What is the most popular add-on category?
The Social & Communication category is the most popular one.

What do you think is the best way to promote and distribute a new add-on in Firefox?
Listing it on AMO is always a good start. We get lots of traffic and very passionate users looking to try out new add-ons. Of course, it’s very important that you give a good first impression! Clearly describing what the add-on does and what makes it unique, including screenshots and choosing the right categories are all critical pieces of a successful launch. Knowing who your potential audience is and approaching it in other channels like online forums is also a good way to start getting some usage.

Why is it different to develop an add-on to the Firefox open source platform, then developing it to other browsers?
From the tech side, but also from the “ideological” perspective…
While there are some commonalities, all browsers offer fundamentally different add-on development platforms. The Firefox add-on platform is unique in that add-ons have the possibility to do pretty much anything that Firefox code can do. This opens up the possibility for add-ons to do truly unique and unexpected things (see NoScript, Pentadactyl, Tree Style Tab). On the other hand, having all of the Mozilla platform at your disposal can be a bit overwhelming, especially for new developers, which is why we have the Add-on SDK, a simplified API that covers the most common development use cases.

 Ideologically, developing an add-on for Firefox means that you’re helping Mozilla move forward its mission of building a better Internet. A healthy add-ons ecosystem is key for the success of Firefox and the Mozilla mission. This includes add-ons that are more on the commercial side and not necessarily open source.

Can you think on an add-on that you would love to see in Firefox that you haven’t seen yet? Maybe not a specific add-on, but more of a specific subject you would like to see add-ons being built for?
There are so many add-ons out there that it’s difficult to keep up with what has been already done. One area where I think more could be done is tab management. Breaking the tab paradigm and making browsers more active agents in people’s daily work. I’d like to see an add-on that treats tabs more like tasks with deadlines that can be grouped into projects. Maybe then I will have fewer than 30 open tabs at all times!

For a new extension developer, starting building a new FF add-on, what is the technology stack they will need to look at before starting?
What are the current recommended technologies / frameworks to work with to have a professional looking tool?
In 2014 I wrote a blog post about this: How to develop a Firefox extension. This should give new developers a good overview of their options. You can get yourself going with just HTML / CSS / JavaScript knowledge, but those seeking to create more advanced add-ons will also need to get acquainted with XUL and XPCOM.

Since add-ons should generally aim to be simple, it’s not that useful to build them on top of third-party frameworks. However, it’s fairly common now for developers to rely on jQuery, Bootstrap, and others, especially for UI layout and effects.

On behalf of the extension developers community, we would like to thank Jorge for sharing his point of view with the Extension Zone users.