Want to know if your everest.yaml is valid? Send it here, and this service will check:
If the file is a valid YAML file, and it has all required fields
If all dependencies exist in the dependency downloader database
Need help getting started? Here is a sample everest.yaml that only has Everest as a dependency, you can open it with any text editor:
Replace YourModName with your mod's name (do not use characters forbidden in Windows file names),
and add your dependencies, making sure the Names and Versions are all lined up vertically.
The Lönn map editor can also add missing dependencies to your mod for you, in the Map > Dependencies menu.
This page only validates the everest.yaml files you place at the root of your mod.
If you want to validate the syntax of other YAML files (like map meta.yamls), use online tools like
this one.