Inertia.js or a separate API: how to choose

When Inertia wins

One team, one deploy, server-driven auth, and UI that is mostly CRUD and workflows. Inertia keeps you shipping without a second API contract to maintain.

When a separate API wins

Multiple clients, partner integrations, or a mobile app that needs a stable public contract. Then the API is a product — treat it like one.

A simple decision rule

Start with Inertia if your primary client is a web app owned by the same team. Extract an API when a second client forces a real boundary — not because a blog said so.