Lunacy

Lunacy is a great pick if you need a free design tool for creating graphics, mockups, or prototypes — especially if your team uses Windows or Linux where Figma's desktop app falls short.

You get a large built-in asset library and full Figma/Sketch file compatibility at no cost, which is hard to beat. The main downside is that it's less mature than Figma, so you may hit occasional bugs or missing features on complex projects.