You can have multiple APIs in one repo.

fern/
├─ fern.config.json
├─ api/ # <--- api #1
│ ├─ generators.yml
│ └─ definition/
│   ├─ api.yml
│   └─ imdb.yml
└─ other-api/ # <--- api #2
  ├─ generators.yml
  └─ definition/
    ├─ api.yml
    └─ imdb.yml

Note: if you have multiple APIs in one repo, you’ll need to use the --api flag when using the compiler, e.g. fern generate --api other-api.