Twitter has joined the Linux Foundation, making its commitment to open source software just a bit more official. Like many operators of high-traffic websites, Twitter relies on open source throughout its data centers, with Linux servers hosting workloads and software projects that make it easier to handle big data and serve up Web content.

The Linux Foundation funds development of the Linux kernel and acts as an emissary on behalf of the technology, while relying on corporate sponsorship from many prominent IT companies that use or build open source software. Twitter joined as a silver member, paying $15,000 for the privilege. The Linux Foundation announced Twitter’s membership today as it gears up for next week’s annual LinuxCon conference in San Diego.

Twitter courted controversy with developers recently with API changes that impose new restrictions on developers of third-party applications. But Twitter Open Source Manager Chris Aniszczyk said joining the Linux Foundation is unrelated and has been in the works for a while.

Twitter is no newbie in the open source world. It uses MySQL to store tweets, and develops its own publicly released fork. Twitter likewise makes heavy use of Memcached and releases its own fork called Twemcache. Cassandra, Hadoop, Lucene, and Pig are other open source tools used within Twitter’s infrastructure. Open source projects created by Twitter include Iago, a load generator for testing services before they hit production; Zipkin, a distributed tracing system; and Scalding, a Scala library that makes it easier to write MapReduce jobs in Hadoop. Twitter is also a sponsor of the Apache Software Foundation and recently joined the World Wide Web Consortium.

Twitter joining the Linux Foundation shows "just how important Linux is becoming to so many of these large scale-out Internet companies that essentially run on Linux and are working to build their infrastructure almost entirely on open source software,” Linux Foundation Executive Director Jim Zemlin told Ars.

Google is another big Web company that is part of the foundation. One missing name is Facebook, but Zemlin hopes to get Mark Zuckerberg and team on board as well. "We would love to have them as a member," Zemlin said. "They do participate in our events around the Open Compute Project so that’s a good thing. Their business runs on Linux as well."