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License Type | Example License(s) | Can someone โpull the ladder upโ after building on your work? | Can you integrate their improvements freely? | Notes |
---|---|---|---|---|
๐ฅ Strong Copyleft | CERN-OHL-S, GPLv3 | โ No โ downstream must open their changes | โ Yes โ everyone must share improvements | Keeps the community free, but restricts proprietary use |
๐ง Weak Copyleft | CERN-OHL-W, LGPL | โ ๏ธ Limited โ changes to original must be open, but addons can be closed | โ Mostly โ improvements to original are open | Allows extensions/plugins to be proprietary |
๐จ Permissive | CERN-OHL-P, Solderpad, MIT | โ Yes โ downstream can close everything | โ No โ unless you get permission, you can't use their closed changes | Maximizes adoption, but allows ladder-pulling |
๐ฆ Dual Licensing | GPL + commercial, or CLA-based | โ ๏ธ Controlled โ you allow copyleft for the public, but retain rights for commercial licensing | โ Yes โ you retain full rights via CLA | Good if you want community contributions and a commercial option |
โช Documentation-only (CC-BY, etc.) | CC-BY, CC-BY-SA | โ ๏ธ Depends โ not designed for functional hardware, may not protect source | โ Unclear โ source availability not enforceable | Use only for manuals, not functional designs |