Seed-Getter is a Minecraft Forge Mod that exploits the hashed seed sent to clients when joining a game to test for a world matching seed. It finds a matching seed by taking in details about where structures and biomes are generated in a world and using those details to deduce seeds until it detects a matching hashed seed.
Feel free to use this mod as you wish for personal use. This mod will never be published on popular mod sites like Curseforge as this mod is technically a cheat mod. Be careful when using this as you may get banned on servers; be warned!
This mod is a WIP. Much of the future plans have been stated above, but more tools for this may come in the future as well, such as using the seed to find out what will be generated in a world and locations of generated features.