MariaDB (version 10.1+ it is MySQL fork) Server for Android totally free.

If you need PHP Apache HTTP or MongoDB server:

! HTTP Server powered by Apache: https://play.google.com/store/apps/details?id=com.esminis.server.apache

! Server for PHP (PHP): https://play.google.com/store/apps/details?id=com.esminis.server.php

! moNERIngAo Server (MongoDB): https://play.google.com/store/apps/details?id=com.esminis.server.mongodb

Website: https://bitbucket.org/esminis/server
Facebook page: https://www.facebook.com/esminis.server

Support this project by translating it: https://poeditor.com/join/project/oQFU4K0vKI