Top PHP REST API Interview Questions & Answers

The most common topics are OOP principles, security (SQL injection, XSS, CSRF), database operations with PDO, error handling, and modern PHP features. Framework questions focus on Laravel (Eloquent, middleware, service container) or Symfony. Senior roles add architecture, performance, and design patterns.

Senior PHP roles expect understanding of framework internals, not just API usage. You should explain how dependency injection containers work, discuss OPcache internals, evaluate architectural trade-offs, and demonstrate experience with testing strategies, deployment pipelines, and performance optimization.

Know one deeply and have familiarity with the other. Most companies use either Laravel or Symfony. Understanding both frameworks' philosophies — Laravel's convention over configuration versus Symfony's explicit configuration — shows breadth. Focus your deep knowledge on whichever the target company uses.

Many PHP interviews include a take-home coding challenge or live coding session. They typically test your ability to build a small API or feature using OOP, database operations, error handling, and testing. Focus on code quality, not speed — clean, tested code with proper structure impresses more than a quick but messy solution.

Major red flags include not knowing about SQL injection prevention, using MD5/SHA1 for passwords, not understanding the difference between == and ===, inability to explain basic OOP concepts, and never having written tests. These suggest a developer who writes vulnerable, hard-to-maintain code.