GLOSSARY / LICENSE TERMS
What is Apache License 2.0?
Apache License 2.0 is a permissive open source license, approved by the Open Source Initiative, that allows broad use, modification, and redistribution while adding an express patent grant. This glossary entry defines it plainly for enterprises and explains why it matters after the relicensing wave.
Definition
Apache License 2.0 is a permissive open source license published by the Apache Software Foundation and approved by the Open Source Initiative. It grants you the right to use, modify, and redistribute the software, including inside proprietary and commercial products, with only light obligations. You must preserve copyright and license notices, include a copy of the license, and state significant changes you make to the files. There is no requirement to release the source of your own work, which is the hallmark of a permissive license.
What makes Apache License 2.0 distinctive
The feature that sets Apache License 2.0 apart from older permissive licenses is its express patent grant. Contributors grant users a license to any patents they hold that are necessarily infringed by their contribution, and the license includes a termination provision: if you bring a patent claim alleging the software infringes, your patent rights under the license end. This gives enterprises a measure of patent certainty that simpler permissive licenses do not provide, which is one reason it became a default choice for large, widely adopted projects.
Apache 2.0 against copyleft and source available
Apache License 2.0 sits at the permissive end of the spectrum. A copyleft license such as the GNU GPL or the GNU AGPL requires derivative works to carry the same terms, which can reach into your own code. A source available license such as the Business Source License or the Server Side Public License restricts certain uses and is not approved by the Open Source Initiative at all. Apache 2.0 does none of this. It is one of the most accommodating licenses an enterprise can rely on, which is why a project leaving it for source available terms represents a real tightening of what you are allowed to do. We explain the broader map in permissive, copyleft, and source available explained.
Why it matters after the relicensing wave
Apache License 2.0 is at the center of the relicensing story because several major projects left it. In 2021, Elasticsearch and Kibana moved from Apache 2.0 to the Server Side Public License and the Elastic License. The fork that followed, OpenSearch, is maintained under Apache 2.0, which is precisely what makes it the open license destination for buyers who want their former footing back. Knowing which versions of which components you run under Apache 2.0, and which carry the newer source available terms, is the basis of a clean compliance picture. Source available is not open source, and the distinction is the whole point, which we cover in source available is not open source and why it matters.
For more definitions, see the full open source license glossary.
COMMON QUESTIONS
Questions buyers ask.
What is Apache License 2.0?
Apache License 2.0 is a permissive open source license approved by the Open Source Initiative. It lets you use, modify, and redistribute the software, including in proprietary products, provided you preserve notices and state changes. It also includes an express patent grant, which is one of its defining features.
Is Apache License 2.0 a copyleft license?
No. Apache License 2.0 is permissive, not copyleft. It does not require you to release the source of derivative works under the same terms, which is the main practical difference from a copyleft license such as the GNU GPL or the GNU AGPL.
Does Apache License 2.0 restrict commercial use?
No. It permits commercial use, including embedding the software in products you sell. This is part of why so many widely used projects adopted it, and why a move away from it, as Elasticsearch made in 2021, is a meaningful change in terms.
Why does Apache License 2.0 matter after the relicensing wave?
Several major projects left Apache 2.0 for source available licenses. Elasticsearch and Kibana moved to the Server Side Public License and the Elastic License in 2021. Knowing which versions you run under Apache 2.0 and which carry the newer terms is the basis of a clean compliance picture.
Is this legal advice about Apache License 2.0?
No. This is a commercial and licensing risk reference, not legal advice. For interpretation of how Apache License 2.0 applies to your specific use, we recommend your own counsel.
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