AliSQL is a fork based on the official MySQL version, maintained by the Alibaba Cloud Database Team. It is currently used in Alibaba Group’s business operations and Alibaba Cloud database services. Recently announced for public beta, it will be open-sourced soon. It’s worth noting that Alibaba previously open-sourced Tengine, based on Nginx, which is now running live on Tmall and Taobao.
The following is the official statement:

AliSQL itself is based on the official open-source version of MySQL and follows the official version releases. It also draws on the community’s best features from other open-source branches such as Percona, MariaDB, WebScaleSQL, and more. The development of AliSQL cannot be separated from the growth of the MySQL community. While benefiting from the community, AliSQL also hopes to give back the technical achievements accumulated over the past few years to the community, helping more individuals and enterprises that use MySQL. This is the path to a healthy development cycle for the MySQL community.