📜 LICENSE CLASS: 📄 WEAK COPYLEFT
Executive Summary: What is it?
The LGPL v2.1 (Lesser General Public License) is a weak-copyleft license positioned between the permissive MIT/Apache family and the strong copyleft of the GPL. It lets you link or integrate an LGPL component into proprietary software without forcing your own code open. If you modify the LGPL component itself, those modifications must be released. Version 2.1 predates the patent and anti-circumvention provisions added in LGPL v3, but for application use the practical effect is the same weak-copyleft boundary.
CFO / Business Impact: What does it cost/risk?
Low contamination risk. You can build proprietary extensions, integrations, or commercial products around an LGPL v2.1 component as long as you do not modify and redistribute the component's own source. Crucially, there is no network clause (unlike AGPL): self-hosting the software, or serving it to staff over your own network, creates no distribution obligation. This makes it safe for internal corporate deployment and for "open core" models where the platform is open and proprietary modules sit alongside it.
Technical Reality: How does it work?
The copyleft is scoped to the licensed component, not your whole application.
- Linking / Integration: Your surrounding application code remains proprietary; you may use the component without sharing your own source.
- Modification Rights: If you change the LGPL-licensed files themselves and distribute the result, you must release those changes under the LGPL.
- No Network Trigger: Running or hosting the software does not count as distribution, so internal and SaaS-style use carry no share-back duty.