Kinchat is an instant messaging web app whose trademark feature was the ability to format chat messages (using bold, italic, underline, etc.) that I originally created for a school invention project. With the subsequent kinchat 1.2, I redesigned the site from the ground up, and wrote a backend from scratch with full support for user accounts (using PHP and MySQL, save for single library to send emails).
Users can add “friends,” view which are online, and then open chat windows to send messages to them in real time. While today there are many accessible technologies and libraries that make implementing real-time chat trivial, at the time (2011), many of those didn’t exist, and I was quite proud of crafting my own solution.