List of Licenses

In the table below, columns with green/orange/red color-coding indicate positive attributes, concerning attributes, and seriously concerning attributes, respectively, of those licenses. Columns with blue/purple/pink/gray color-coding indicate which indicate different types which are not clearly better than another type.

• Readability refers to whether it uses clear, plain language that even non-lawyers can understand. A few modern software licenses have been developed in the past two years which are written by lawyers in plain English and, compared to traditional licenses, are more legally complete and clarify some legal ambiguities which have caused issues in the open-source software world; however, they have not established a large user community yet.
• Patent Grant refers to whether the licensee is granted rights to make, use, or sell the licensed work.
• Modification Notices refers to whether the licensee is required to add notices listing each modification they make. While there can be huge administrative complexity and confusion for open-source projects/ecosystems to maintain these notices, they can also protect the reputations of risk-averse licensors if something goes wrong due to a modification made by a licensee.
• Reciprocality, for reciprocal licenses, refers to the requirements on a licensee after they make an adapted work using the licensed work.
  • Trigger describes when licensees must share other work
  • Reach describes what work licensees must share
  • Licensing describes on what terms the licensees must share their work
  • Distribution describes how licensees must share that work
• Cure Provision refers to whether a licensee who unknowingly violates the terms of the license (usually related to notices such as attribution or modification, or to reciprocality) has a legally-protected path to take corrective action to comply with the license before the license is permanently terminated for them.

Open-Source Licensing Options

List of License Combinations

The following pairings of software and hardware licenses make the most sense together for consistency between software and hardware licensing:

• Strongly Reciprocal:
  • (Human-readable) CERN-OHL-S + Parity: CERN-OHL-S is a somewhat readable license, while Parity is the most popular human-readable license. Parity enables license compatibility by allowing permissive licensing of derived works, which is a big plus for encouraging other people to build open-source applications using our libraries. Caveats: they have different requirements on modification notices and different requirements on reciprocality. Caveats: Parity is still a new license (almost on the bleeding edge in terms of modern licenses).
  • (Popular, with modification notices and sharing to recipients) CERN-OHL-S + GPL: this is a combination of two well-established licenses, and both have the same requirements on reciprocality of adapted works.
• Weakly Reciprocal:
  • (Human-readable) CERN-OHL-W + MPL: these are both popular options and both are human-readable. Caveats: CERN-OHL-W and MPL differ slightly in the reach scopes of their reciprocality terms, but the differences seem reasonable between hardware and software.
  • (Popular, with modification notices) CERN-OHL-W + LGPL: these are the two most popular options. Caveats: GPL is already very long, and LGPL adds even more text on top of it, and the trigger scope of reciprocality for LGPL is nuanced and hard to fully understand.
• Permissive:
  • Apache + SHL: this would be a nice combination which unifies the terms and conditions between software and hardware.
  • CERN-OHL-P + BlueOak: CERN-OHL-P is a somewhat readable license, while BlueOak is the most established human-readable software license. Caveats: BlueOak is still a new license (almost on the bleeding edge in terms of modern licenses).
  • CERN-OHL-P + BSD-2-Clause-Patent: CERN-OHL is a popular hardware license family, while BSD-2-Clause is a popular software license family.

Any media which is not a source file for software or hardware (e.g. graphics, creative materials) can be licensed as either CC-BY or CC-BY-SA depending on whether the software & hardware licenses are permissive or reciprocal.

Open-Source License Combinations