TempWorks OpenAPI: authenticate via OAuth2 (Service, Service Rep, or Web User flows)

Steps

1. Choose the correct OAuth2 user type for your integration: Service (server-to-server), Service Rep (staffing agency employee via code flow), Web User Employee, or Web User Contact.
2. For a Service (machine-to-machine) integration, POST to https://login.ontempworks.com/connect/token with grant_type=tw_vendor_service_credentials, client_id, client_secret, and acr_values set to 'tenant:{tenant} pid:{product-instance-id}'.
3. For Web User flows, POST the same token endpoint with grant_type=tw_vendor_webuser, usertype set to WebUserEmployee or WebUserContact, plus the end user's username/password.
4. For Service Rep users, implement the OAuth2 authorization code flow that redirects to the TempWorks Login Server and back to your app with a bearer token (sample .NET/Node projects are linked from the docs).
5. Attach the returned bearer token as Authorization: Bearer {token} on calls to api.ontempworks.com, or fall back to HTTP Basic auth (AccountSid/AuthToken) or the x-tw-token header/query-string token if OAuth isn't set up yet.