API's for Service Providers Application Integration

Our Client's Logistics Service Provider are in the process of creating their own application which will include the functions of Tender Acceptance, Dock Scheduling, and Driver Assignment, which are currently performed manually in OTM. This will streamline the process as per the client.

What the client needs is an API documentation for OTM integration with regards to the above functions, can you please provide a list of API's (if they exist) which can integrate these functions or any documentation on the same?