DoBackup is a free software that generates backups of MySQL databases. Written in PHP, the tool can be used on the many platforms where this language is supported, including Windows, Mac OS and Linux.
GPMID is a free software that supports Guitar Pro files. It can retrieve various information from tablatures and can notably convert them to MIDI streams, making them easy to listen with a media player.
Htmlys is a free library that allows developers to parse web content and react to HTML tokens (such as the ubiquitous tags) discovered while parsing. The library is distributed both as a dynamic extension for PHP and as a dynamic module for Python and is intended to extend the facilities offered by both programming languages.