📜 Software Licenses: Overview & Use Cases
| License Name | Type | Allows Use In | Restrictions / Notes | When to Use It |
|---|---|---|---|---|
| AGPL-3.0 | Strong Copyleft | Open-source only | Must disclose source even for web/SaaS usage | You want to protect server-side software and enforce open-source sharing |
| Apache-2.0 | Permissive | Open + Commercial | Must include license, NOTICE file, and patent grant | Enterprise-safe permissive license with patent protection |
| BSD-2-Clause | Permissive | Open + Commercial | Minimal: just keep copyright & license | Lightweight permissive license (similar to MIT) |
| BSD-3-Clause | Permissive | Open + Commercial | Like BSD-2, plus no endorsement clause | Prefer BSD-2 but want to prevent implied endorsements |
| BSD-4-Clause | Permissive | Open + Commercial | Deprecated; includes advertising clause | Avoid unless required for legacy compatibility |
| BSL-1.0 (Boost) | Permissive | Open + Commercial | Very permissive with minimal restrictions | Used in Boost C++ libraries; good for academic/research |
| CC-BY-4.0 | Attribution (Content only) | Any | Attribution required; not for code | Use for docs, logos, or designs — not source code |
| CC0-1.0 | Public Domain | Any | No rights reserved (no attribution required) | Best for public domain releases (not recommended for important code) |
| EPL-2.0 (Eclipse) | Weak Copyleft | Open + Commercial | File-level copyleft; contributors grant patent rights | Good for Eclipse plugins or modular Java apps |
| GPL-2.0 | Strong Copyleft | Open-source only | Must open source full app if combined or distributed | Classic copyleft license; avoid mixing with Apache-licensed code |
| GPL-3.0 | Strong Copyleft | Open-source only | Like GPL-2.0, adds anti-Tivoization and better patent terms | Protect FOSS fully; use when sharing code is a core value |
| ISC | Permissive | Open + Commercial | Simple, MIT-like; very concise license | Good lightweight permissive option, especially in networking projects |
| LGPL-2.1 | Weak Copyleft | Mixed | Library linking allowed; changes must be shared | Use for open-source libraries with commercial use allowed |
| LGPL-3.0 | Weak Copyleft | Mixed | Like LGPL-2.1 with added protections | Prefer over LGPL-2.1 for modern legal safety |
| MIT | Permissive | Open + Commercial | Must include license and copyright notice | Most popular open license; great for projects meant for wide reuse |
| MPL-2.0 | Weak Copyleft | Mixed | Copyleft only applies to modified files | Great for projects that want some openness without forcing full disclosure |
| UNLICENSE | Public Domain | Any | No copyright claim, no liability | Use only if you want to waive all rights entirely |
| WTFPL | Public Domain / Humor | Any | “Do What the F*** You Want” license | Mostly humorous; legally valid but not suitable for professional use |