"API First" offers several advantages:

Improved system integration. “API First” encourages developers to carefully consider system interactions from the project’s outset, reducing the need for ongoing modifications during development.

Enhanced collaboration and quality. APIs serve as a shared specification within the organization, allowing developers, testers, and DevOps to work independently. Agreeing on APIs at the project’s beginning helps eliminate uncertainties and boost software quality.

Increased scalability. With defined interfaces for each service, scaling becomes more manageable by spinning up new instances and adjusting load balancer settings.