Is Frame Data Overlay & Hitbox Visualizer Tools free?

Yes. Frame Data Overlay & Hitbox Visualizer Tools is released under Community Free and costs nothing. Neither it nor Brawlhalla has any paid content.

What do I need to run Frame Data Overlay & Hitbox Visualizer Tools?

Brawlhalla, which is itself free. Frame Data Overlay & Hitbox Visualizer Tools is an add-on and will not run standalone.

The PlayBound Launcher installs it in one click from Brawlhalla's mods list. You can also install it by hand — full steps are on this page.

Roughly 15 MB, on top of the base Brawlhalla installation.

Yes. The source is published at github.com/Brawlhalla/TrainingTools under Community Free.

Frame Data Overlay & Hitbox Visualizer Tools — Free Brawlhalla Mod · PlayBound