The Firefox Marketplace is the gateway to the Firefox OS app ecosystem. In building it, we found a lot of hard problems surrounding usability and experience. In this presentation, Matt Basta talks about how the guys of "Project Fireplace" helped us overcome the barriers of deploying an app that needs to work well even at the edges of the earth. This includes supporting low-end devices with high-latency connections, L10n, unit and functional testing, and staying sane through the whole process. Stick around for a demo of Fireplace's page rendering framework, called The Builder.