Looking to attract more developers, Adobe Systems will release the Flex 3 development kit with the Mozilla Public License.
The company on Wednesday is expected to announce the move, which will start when it releases a beta of the next version of Flex, code-named Moxie, in June.
By the time Adobe releases the final version of Moxie, which will be called Flex 3, near the end of the year, it expects to have a fully functioning open-source project, company executives said Tuesday. Adobe intends to use the Mozilla Public License.
The company said it will open-source the Flex software development kit, which includes a compiler and libraries designed to speed up development. It plans to continue to sell Flex Builder, an Eclipse-based development tool, and Flex Data Services, server software for accessing corporate databases.
Flex is one of a growing number of alternatives for building so-called rich Internet applications, which sport an interactive front-end interface. Using the development framework, programmers create an application that can run within Adobe's Flash Player or Apollo, its "player" for desktop applications.
The company chose to create an open-source project for the Flex software to garner good ideas and contributions from developers outside Adobe, said Jeff Whatcott, vice president for product marketing at Adobe's enterprise and developer business unit.
The move is also meant to appeal to open-source developers who shun closed-source and proprietary products. Adobe already offers the Flex software development kit for free and provides the source code.
"For some people, (open source) is a philosophical requirement, a sign of integrity and trust in a vendor," Whatcott said. "This will close that gap and address any lingering doubts they have about our openness and commitment to community."
The company is making the transition to open source now because the Flex technology is mature and there is growing interest among developers and rich Internet application development, Whatcott said.
Adobe will initially provide nightly updates of Moxie code and will publish a bug database when the software goes into beta in June. When it is released near the end of the year, Adobe will be able to accept outside contributions.
The move follows Adobe's donation last November of its ActionScript virtual machine to the Mozilla Foundation, the makers of the open-source Firefox browser.
Offering free or open-source development tools has become nearly de rigueur for software vendors. Like many companies, Adobe intends to make money via associated software, like higher-end tools and server software.