MySQL - The world's most popular open source database
Freshservice - Freshservice: the one-stop cloud solution for all your IT management needs.
PostgreSQL - PostgreSQL is a powerful, open source object-relational database system.
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
SQLite - SQLite Home Page
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.