This app allows you to create your own superflat presets. Every aspect can be customized. Only for PC.
Not sure which blocks can be set on fire or picked up by endermen? The Block Compendium will answer that and much more, giving you an up-to-date list of all blocks you can use for your next project.
Spawn Chunks Reader provides a quick and easy way to figure out your world's spawn chunks and coordinates by submitting your level.dat file.
With this Seed Finder App, you can find Minecraft seeds based on where you want to have slime chunks.