UltimMC is a custom launcher for Minecraft which allows you to manage multiple instances and use offline ("cracked") accounts while keeping as close as possible to the original.
Titan Launcher Alternatives
Titan Launcher is described as 'Free cracked launcher for Minecraft - "Lightweight" and straightforward, feature-less but offers a great library and requires no installation' and is a minecraft launcher in the games category. There are more than 10 games similar to Titan Launcher for a variety of platforms, including Windows, Linux, Mac, Android and Flathub apps. The best Titan Launcher alternative is Zalith Launcher, which is both free and Open Source. Other Titan Launcher like games are PolyMC, TLauncher, PojavLauncher and MojoLauncher.