SQLite

Details

The project is provided in the public domain.

There are some extra non-FOSS extensions made available to purchase for encryption and compression but these are kept as distinct offerings, not mixed with FOSS offerings by default in distribution, and don’t appear to be conflated as part of SQLite itself within their website. They’re clearly referenced as separate extensions. Significant parts of the project’s test suite, referred to as the “TH3 test harness”, is not included in the public domain sources but is instead available for purchase.

The project strongly limits contribution in the interest of keeping “SQLite in the public domain and ensure that the code does not become contaminated with proprietary or licensed content”.

SQL appears to gain funding by selling legal warranties, extra licenses for its extensions and via providing support offerings. It also gains funding from members becoming part of the SQLite Consortium.