I haven't been able to spend a ton of time recently on Open Source, but here are some of my past projects:
A JSON Schema based editor. You provide a JSON Schema and it generates an HTML form to edit JSON data that conforms to the schema.
Written in vanilla JS with no dependencies. Works standalone, but can also integrate with multiple 3rd party CSS frameworks, icon libraries, and templating engines.
A PHP class for formatting and highlighting SQL statements.
Included as part of Symfony2's debug toolbar. Over 1.6 million installs through Packagist.
A full featured PHP framework for displaying reports from any data source, including SQL and MongoDB.
File System Cachehttps://github.com/jdorn/FileSystemCache
A PHP class for caching data in the filesystem.
Supports TTL, "Newer Than", proper file locking, and grouped cache keys.