MIT, Apache 2.0, BSD
These are the "business-friendly" licenses. Think of them like a gift with a small sticky note attached. The note says: "Here is the code. Use it, change it, sell it, close-source it. I don't care. Just don't sue me, and keep my copyright notice in the file." That's essentially the entire obligation.
1. MIT License:
The shortest and most widely used open-source license. The full text fits on a single page. Its core grant: "Permission is hereby granted, free of charge, to any person obtaining a copy of this software... to deal in the Software without restriction." The only obligation is to include the original copyright notice and the license text in your distribution.
- Risk Level: Very Low.
- Enterprise Usage: Approved almost everywhere, no legal review required.
- Examples in the wild: React, Rails, jQuery, Lodash.
2. Apache 2.0:
Similar to MIT in permissiveness, but with one crucial addition: an explicit Patent Grant. It says that every contributor to the project grants you a royalty-free license to any patents they hold that are necessarily infringed by their contribution. This protects your company from a specific attack vector: someone releases open-source code, you use it, and then they sue you for infringing the patents embedded in that code. Apache 2.0 closes that loophole by contract.
- Risk Level: Very Low.
- Enterprise Usage: Preferred for large, high-stakes projects. Kubernetes, TensorFlow, and most of the Apache Software Foundation's projects use this license for exactly this reason.
- One nuance: Apache 2.0 and GPL v2 are incompatible. You cannot combine Apache 2.0 code with GPL v2 code in the same binary. GPL v3 resolved this incompatibility.
3. BSD Licenses (2-Clause and 3-Clause):
Functionally similar to MIT. The 3-Clause variant adds a "non-endorsement" clause: you cannot use the original author's name to promote your derived product. Practically, this rarely matters for enterprise use.
Interviewers often ask: "What's the difference between MIT and Apache 2.0?" The answer that impresses: "Both are permissive and allow commercial use with minimal obligations. The key difference is Apache 2.0's explicit patent grant, which protects users from patent litigation by contributors. This is why Apache 2.0 is preferred for enterprise-grade open-source projects — it closes a legal attack vector that MIT leaves open."