Business Source License
The Business Source License (SPDX id BUSL-1.1) is a software license which publishes source code but limits the right to use the software to certain classes of users. The BUSL is not an open-source license, but is a source-available license that also mandates an eventual transition to an open-source license. This characteristic has been described as a compromise between traditional proprietary licenses and open source.
The originator of the BUSL is MariaDB Corporation AB, where it is used for the MaxScale product, not for the flagship MariaDB.