Pancake Studio is a program to assist with modding Source games such as Team Fortress 2. It supports Source engine subtitles, and can load sound scripts to make captioning extremely easy. It also has a tool to easily extract game content from your GCFs.
You need a Steam account and at least one source game. In order to compile captions you also need the Official Source SDK.
A feature introduced in 10.3.13 is the Console Simulator, which will simulate your TF2 scripts (or whatever Source game) without having to open the game every time you want to test out a script. It also has some debugging features not present in the Developer Console and debugging for Source Script assemblies.
These are the downloads you’re looking for
Pancake Studio 10.9.24
Pancake Studio Downloads
Team Fortress 2 Captions
Post engineer update.