What is cpl?

CPL, short for Common Public License, is a free software license created by IBM. It's considered an open-source license approved by the Open Source Initiative (OSI).

Key Characteristics:

  • Reciprocity: CPL is a weak copyleft license. This means modifications to the CPL-licensed code must be released under the CPL. However, distributing the CPL-licensed code as part of a larger work does not require the entire work to be licensed under the CPL. Only the modified CPL component needs to be.

  • Patent Grant: The CPL includes an explicit patent grant from contributors to recipients of the software, protecting users from patent infringement claims related to the contributed code.

  • Termination: The license automatically terminates if the licensee initiates patent litigation against the licensor or a contributor, asserting that the CPL-licensed software infringes a patent.

  • Choice of Law: The CPL specifies that New York law governs the license.

  • Relationship to EPL: The CPL is the predecessor to the more commonly used Eclipse Public License (EPL). The EPL is essentially a modified version of the CPL, addressing some perceived shortcomings. Because of the EPL's popularity, the CPL is not as widely used today.

In summary, the CPL is a copyleft open source license that offers a patent grant, but is not as widely used as its successor, the EPL.