Vanilla Forums is a modern, lightweight, and open-source forum software written in PHP. Vanilla Forums has many features, settings, and areas that can be customized. The flexibility and free nature of Vanilla Forums (plus its modern design and feature set) makes it an attractive choice for anyone looking to start their own forum to talk to people on. Installing Vanilla Forums on Debian 9 is an easy task if you follow the steps below carefully. Let’s begin with the installation.