Geyser is a proxy, bridging the gap between Minecraft: Bedrock Edition and Minecraft: Java Edition servers. The ultimate goal of this project is to allow Minecraft: Bedrock Edition users to join Minecraft: Java Edition servers as seamlessly as possible to allow for true cross-platform.
Geyser is a middleware, which translates all the incoming and outgoing packets. With this being said, Geyser works as a standalone proxy, meaning you can use it to join any modern Minecraft Java server. Geyser can also be installed on your server as a plugin, so you can easily make your server compatible with Minecraft: Bedrock Edition.