You can download the latest version of ExtremeLaunch here: https://extremelauncher.net/_cdn/ExtremeLauncher.exe
The latest version of ExtremeLauncher supports all versions of Minecraft, keep in mind you need Java installed on your PC in order to run Minecraft.
Minecraft versions up to and including Minecraft 1.16 will work with Java 8, Minecraft 1.17 requires Java 16 or higher, and Minecraft 1.18 and above requires Java 17 or higher you can find more information in Get java section.
If you find a bug or issue with ExtremeLauncher contact us with as much information as possible (Windows version, Java version, Launcher version, Minecraft version, mods list, etc).
Mods like OptiFine and Forge should generally work out of the box, you can install them as with any other Launcher.
.NET Framework 4.7.2 is required for ExtremeLauncher to run, it should already be preinstalled on most of the system, if not you can download it from Microsoft for free or from our mirror.