The Fulcrum REST API's OpenAPI JSON can be found at this link: https://docs.fulcrumapp.com/openapi/5f29a2f7dbacf8001851acc1
You can use this URL to import all REST API endpoints into HTTP request apps like Postman. First open Postman and click the Import button
Paste the URL into the resulting window and then import the API as a Postman Collection
Once imported, click on the top level REST API collection, click Authorization, and replace {{apiKey}}
with your own API token
You are now ready to start sending requests!