18Software Engineering · Interview Prep · Free
PHP Developer interview questions — and how to answer them.
These are the questions PHP Developer candidates are most likely to face, from openers to the hard ones — each with a note on what a strong answer covers. Want more, tuned to your level? Use the free generator below.
What interviewers look for in a PHP Developer
- Concrete examples of systems you've built, with the trade-offs you weighed
- How you debug — the process, not just the fix
- Collaboration signals: code review, disagreements, mentoring
Likely PHP Developer interview questions
1. Tell us about your experience with PHP. What versions have you worked with and what projects have you built?
Mention specific PHP versions, frameworks used, and 2-3 concrete projects with their scope and your contributions.
2. Describe your experience with object-oriented programming in PHP. Can you give an example of when you used OOP principles?
Explain classes, inheritance, polymorphism, or design patterns with a real project example showing problem-solving.
3. What databases have you worked with and how do you typically interact with them in PHP?
Mention MySQL, PostgreSQL, etc., and discuss use of ORM libraries like Eloquent or Doctrine, prepared statements for security.
4. Walk us through your process for debugging a PHP application. What tools do you use?
Cover error logging, var_dump/print_r, debuggers like Xdebug, browser dev tools, and log analysis strategies.
5. How do you handle authentication and authorization in PHP applications?
Discuss password hashing (bcrypt/Argon2), session management, JWT tokens, role-based access control, and security best practices.
6. Tell us about a time you had to refactor legacy PHP code. What challenges did you face and how did you overcome them?
Show specific refactoring steps, testing strategy, communication with team, and measurable improvements in code quality or performance.
7. How do you approach writing unit tests in PHP? What frameworks or tools do you prefer?
Mention PHPUnit, code coverage targets, mocking, testing strategies (unit vs integration), and how you ensure testability.
8. Describe your experience with PHP frameworks. Which have you used deeply and why would you choose one over another?
Compare Laravel, Symfony, CodeIgniter, or others; discuss architecture, conventions, ecosystem fit, and project-specific trade-offs.
9. How do you optimize PHP application performance? Give an example of a bottleneck you identified and fixed.
Cover profiling tools, database query optimization, caching strategies (Redis/Memcached), code efficiency, and metrics used.
10. Explain how you would design a RESTful API in PHP. What considerations do you keep in mind?
Discuss HTTP methods/status codes, request/response formats, error handling, versioning, rate limiting, documentation, and security.
11. Describe your experience with CI/CD pipelines and deployment processes for PHP applications.
Mention Git workflows, automated testing, Docker containerization, deployment tools, environment management, and rollback strategies.
12. Tell us about a complex technical problem you solved in PHP that required deep problem-solving. How did you approach it?
Showcase research methodology, breaking down complexity, consulting documentation/community, testing hypotheses, and documenting the solution.
Want to practice answering live with scored feedback? Try the Mock Interview Coach.
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