Mozilla has announced the second phase of its Phones for Apps service for Firefox OS, in a bid to further boost the number of apps available in its Firefox Marketplace.

The first phase was launched in May with developers receiving Geeksphone Keon Firefox OS Developer Preview phones to help them develop apps and games. Phase two is aimed at developers interested in porting their existing HTML5 apps to the Firefox OS platform.

Firefox OS uses HTML5 as its app programming language, opening the market to web developers as well as mobile publishers. The OS is designed to bring smartphone functionality at a reduced price.

In order to participate in the first phase of Phones for Apps, developers needed to show Mozilla “a great app idea and the skill to build it”. Mozilla said thousands of developers from around the world applied for a preview device during the first phase of Phones for Apps, with numerous new titles listed in Firefox Marketplace as a result.

Telefonica became the first operator to launch a device powered by Firefox OS when it made the ZTE Open available to subscribers in Spain in July. The operator group then launched the ZTE Open and Alcatel OneTouch ZTE in several Latin American markets in August.