Mern-stack interview usually starts with a short coding test where you solve basic JavaScript problems like arrays, loops, or string manipulation. After that, a technical round focuses on React and Node.js concepts. In React, interviewers commonly ask about state, props, hooks like useEffect, conditional rendering, controlled inputs, and how you manage API calls. For Node.js and Express, they check whether you can explain REST APIs, CRUD operations, middleware, routing, and how frontend communicates with backend using fetch or axios.