LGPL30

The GNU Lesser General Public License version 3.0 (LGPL 3.0) is a copyleft license designed to promote the sharing and modification of software while allowing certain types of proprietary integration. Released in 2007 as part of the GNU Project, it is a successor to the LGPL 2.1 and aims to address concerns raised about its predecessor, particularly regarding dynamic linking and patent protections.

LGPL 3.0 retains the core principles of copyleft licensing, ensuring that derivative works remain free and open-source. However, it introduces stricter conditions for dynamic linking, requiring that modifications to linked libraries be made available under the same license. This helps prevent proprietary software from relying on LGPL-licensed code without contributing back improvements. The license also includes stronger protections against patent lawsuits, requiring contributors to grant patent licenses to all users of the software.

One key distinction of LGPL 3.0 is its "tirade clause," which prohibits linking with software that contains a "tirade" (a message or notice that violates the license terms). This prevents proprietary software from using LGPL-licensed components while suppressing or altering license-related notices. The license also clarifies that it applies only to the specific files it covers, allowing other parts of a program to remain proprietary.

LGPL 3.0 is widely used in open-source projects, particularly those involving libraries and components intended for integration into proprietary software. It strikes a balance between fostering collaboration and protecting the freedom of users to modify and distribute software. The license is maintained by the Free Software Foundation (FSF) and is part of the GNU General Public License (GPL) family.