I built a war paint viewer for TF2. It recreates the game's paint compositor and lighting, so you can preview war paints across wear levels, teams, and seeds.

It also has sheens, unusuals, the in-game lighting environments, and a first-person view. You can export transparent screenshots or turntable animations, and load your own paint definitions and textures if you're making something custom.

It's free and open source.

Viewer: https://rhgx.github.io/warpaint-viewer/

Source: https://github.com/Rhgx/warpaint-viewer

Not affiliated with Valve.