API-First vs Code-First Development

When frontend and backend teams build a feature at the same time, they need to agree on the interface before their assumptions drift apart. Suppose a bookstore's web team builds a review form while the backend team implements review storage. The web team expects a successful submission to identify the new review, but the backend returns a generic success message. Both teams can finish their assigned work and still discover an integration problem when they connect the pieces.

Development workflow determines when teams make interface decisions, who reviews them, and how those decisions reach the implementation.

This chapter compares API-first and code-first development, explains their trade-offs, and shows how either approach can maintain a reliable contract.