Following the lead of Facebook and other companies of the Web 2.0 vanguard, Yahoo took a big step toward opening itself up to third-party applications Friday.

Independent applications have been immensely popular on Facebook since the startup offered access to some of its programming interfaces, or APIs, last year.

Yahoo on Friday accelerated its efforts to do the same. “We need to move as quickly as possible here,” said David Filo, chief Yahoo (pictured).

At the company’s Open Hack Day, which drew 300 outside developers, Yahoo provided a first look at APIs and application building tools developed under its Open Strategy. The APIs and tools will let developers tap into user data and connect their programs to Yahoo’s many Web properties.

“We really have to tap into the creativity and experiences of other companies (and) students from all over the world,” said Filo.

The early feeback was mixed. “I think it is the right way to go for them,” said Jerry Su, a software engineer at Xoopit in San Francisco. “They have been making a lot of products for themselves and not opening up to the outside world.”

But Justin Kruger, a software engineer at Hi5, said the new tools weren’t compatible enough with some widely used Internet software, such as Flash.

By Mark Boslet, Editor at Large.