The Open Source Initiative (OSI) is the standards body that defines and certifies "open source" licenses, representing the pragmatic wing of the FOSS movement that emerged from the open-source-schism-and-dotcom-1998-2004.
The OSI was founded in late February 1998 by eric-raymond and bruce-perens, days after the foresight-open-source-meeting-1998 where the term "open source" was coined by christine-peterson. Its founding documents were the open-source-definition — adapted by Perens from the Debian Free Software Guidelines — and the institutional mission of certifying licenses as "OSI-approved." Certification gave the term "open source" a definable meaning: a license is open source if and only if it meets the ten criteria of the Open Source Definition.
The OSI's certification function proved strategically important during the open-source-schism-and-dotcom-1998-2004 and mainstream-adoption-and-corporate-embrace-2005-2014 eras. Corporations adopting open source practices needed assurance about what "open source" meant legally and practically; OSI certification provided that assurance. The apache-license-2, mit-license, bsd-license, and gpl-v2 all carry OSI certification, giving them a common designation despite very different philosophical orientations.
The OSI explicitly represents the pragmatist position in software-freedom-vs-open-source: it accepts permissive licenses that the free-software-foundation would also consider free, but it avoids the FSF's ethical framing. Where the FSF asks "does this license protect user freedom?", the OSI asks "does this license meet the Open Source Definition criteria?"
Perens resigned from the OSI in 1999, citing concerns about license proliferation and the organization's direction. License proliferation became a persistent problem through the 2000s as organizations submitted idiosyncratic licenses for certification; the OSI has periodically run license rationalization processes to address it.
In the modern-foss-and-sustainability-crisis-2015-present era, the OSI has engaged with "source-available" licenses (such as sspl-bsl) that companies use to restrict commercial use while maintaining the appearance of openness — a category the OSI refuses to certify as open source. This position has put the OSI in conflict with companies like MongoDB (SSPL) and HashiCorp (BSL), and renewed debate about whether the Open Source Definition is adequate to the modern landscape.