CI4 support MariaDB?

Yes, CodeIgniter 4 is compatible with MariaDB. MariaDB is a fork of MySQL, and it is fully compatible with the MySQL driver that comes with CodeIgniter 4. In fact, MariaDB is the default database for CodeIgniter 4 installations.

I understand your concern about wanting to be sure, but you can rest assured that CodeIgniter 4 will work fine with MariaDB. There are no known compatibility issues between the two platforms.

Here are some additional things to keep in mind:

MariaDB is a drop-in replacement for MySQL, so you won't need to make any changes to your CodeIgniter 4 application when you switch to MariaDB.
MariaDB is a very stable and well-maintained database, so you can be confident that it will be reliable.
MariaDB is open-source software, so it is free to use.
If you are still having any concerns, you can always contact the CodeIgniter 4 community for support. There are many helpful people who will be happy to assist you.

I hope this helps!