GFXComet is a great place for getting assets for GFX, logo design, and UI design.
Shotcut is probably the second-best FOSS video editor, after Kdenlive. Some prefer it because it’s a lot faster than Kdenlive.
Lua-minify, is an amazing Lua beautifier that actually works. There’s a Studio plugin for it.
Here’s a Scoop bucket for most of the popular Roblox development tools. What’s a Scoop bucket? A Scoop bucket basically adds a colleciton of programs to the Windows package manager “Scoop”. If you are using the Scoop Viewer, it provides a one-click install for all the top Roblox development tools such as Rojo, Roblox FPS Unlocker, roPresnece (a Roblox Discord Rich Presnece), and rbxlx-to-rojo.
AeroGameFramework is probably one of the most popular Roblox game frameworks out there.
Knit is another Roblox framework created by the same developer of AeroGameFramework, it was created in an attempt to solve the issues of AeroGameFramework. Knit is not that stable yet.
EasyNetwork is a great tool that advanced Roblox scripters should look into.
Here is a list of Roblox tools which you can use with Rojo, and benefits of using Rojo. I highly recommend that you read this if you are interested in offsite tooling like Rojo.
Studio Bridge is the only Rojo alternative still in development. Rojo is a lot better, but if you want something simpler or something written in JavaScript, Studio Bridge is probably your only option. For most people, I would recommend Rojo.