Taxpayers who wish to directly integrate APIs, without going through ASP or GSP or any solution provider, can go for direct API integration.
You would need to
Register all your GSTINs. For this a login for Taxpayer user to be created
Sign up as API Integrator and get the details needed for APIs. Detailed documentation for solution providers is available here.
Important to note, Taxpayer user and API integrator are distinct users. Hence, use separate email while signing up for the respective user type.
need real-time e-invoice generation can opt for direct API integration.