Apps with 'Custom Scripts' feature

Lutris is an open source gaming platform for GNU/Linux. It allows you to gather and manage (install, configure and launch) all your games acquired from any source, in a single interface.

Tampermonkey is a free browser extension and the most popular userscript manager for Blink- and WebKit-based Browsers like Chrome, Opera Next and Safari.

The smallest and fastest browser, but so powerful with customization.

You are a PHP developer and you want: a modern development environment, a reliable infrastructure, established standards and an up2date run-time. But – do you really want to setup and maintain everything by yourself?

From simple lists to complex data applications, with Databuilder, your solution will be up and running in no time. Create a custom online database in the cloud with no coding required and take your collaboration to the next level.

The xbar app lets you put the output from any script or program right in your macOS menu bar. And it's completely free. An impressive number of plugins have already been contributed by a wide range of developers, and this site makes it easy to find them.