PHP Developer Interview Questions

Looking for a PHP Developer to join your team? Revelo can help you source and vet top-tier candidates.

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 Interview questions

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The interview process for any hiring role is a crucial step that requires careful thought and preparation. When it comes to recruiting a PHP developer, the same holds true. It's not simply about evaluating the candidate's technical capabilities in PHP but also their soft skills, personality, and problem-solving abilities. 

Preparing for such an interview requires a comprehensive understanding of what to look for in a candidate and how to ask the right PHP developer interview questions. With help from Revelo, this process can be much smoother. We have the tools and resources to help you source talented developers, line up interviews with the right candidates, and coach you through the interview process.

This article will advise you on what to look for in a PHP developer and how to ask the right PHP interview questions to assess their knowledge and capabilities. With these tips in mind, you can ensure that every interview is set up for success.

What Is a PHP Developer?

A PHP developer is a professional who develops applications, websites, and programs using PHP, a popular server-side scripting language. They are responsible for writing, testing, and maintaining the code for web applications to ensure their functionality and performance.

Their work typically involves writing server-side web application logic, developing back-end components, connecting applications with other web services, and supporting front-end developers by integrating their work with the application. They also often work on projects requiring integration with languages like JavaScript, HTML, and CSS.

PHP developers work on various projects, from creating simple websites to developing complex web applications or content management systems. Therefore, if your organization is building a dynamic website or a web application that requires server-side scripting, like an e-commerce site, a blog platform, or a social networking site, you will want to hire a PHP developer.

Entry-Level PHP Developer Interview Questions 

For an entry-level PHP developer, you're not looking for extensive experience but a solid understanding of the basics, a willingness to learn, and a passion for web development. Therefore, your focus should be on the candidate's raw potential and ability to adapt to the role. 

Below are a few entry-level PHP interview questions and answers to get you started.

Explain what PHP is and give some examples of its common uses.

While this question may seem obvious, it's essential for setting the tone of the interview and will help gauge how well the candidate can articulate themselves. A good answer should explain that PHP is a server-side scripting language used to create websites, web applications, and dynamic content.

What's the difference between PHP's include() and require() functions?

Syntax and functions are the cornerstones of a PHP developer's knowledge, so this question will give you an idea of the candidate's technical capabilities and ability to grasp complex concepts. The correct answer should state that while both functions include files in a script, require will issue a fatal error (or critical error) if the file is not found, while include will only issue a warning.

How would you handle form submission in PHP? Could you walk us through the steps?

Form submission is a common task for PHP developers, so it's important to understand the candidate's approach and level of detail. This is a great question to assess the candidate's problem-solving skills and technical proficiency. A good answer should include steps like setting up a form handler, creating an HTML form, creating a PHP script to handle the submission, adding validation logic, and displaying responses.

What is your approach to connecting a PHP application with a MySQL database?

A thorough understanding of databases is essential for a PHP developer because most web applications require a connection to a database to function properly. An ideal answer should include steps like connecting to the database, setting up a query, executing the query, and displaying the results. It would be even better if the candidate could describe more advanced techniques like prepared statements and parameterized queries.

What are PHP sessions, and why are they important? Provide an example of when you might use them.

PHP sessions are an important concept for any PHP developer, as they help store user information between page requests. This question will allow you to assess the candidate's knowledge of the language and their ability to apply it in real-world scenarios.

A good answer should explain that PHP sessions store data on the web server side and keep track of user information, like preferences and settings, between page requests. One example would be using PHP sessions to store user information in a shopping cart application or a login system for a website.

Mid-Level PHP Developer Interview Questions

A mid-level PHP developer should demonstrate an advanced understanding of the programming language, focusing on problem-solving skills and technical proficiency. Therefore, you will want to assess their ability to handle complex tasks, experience with different frameworks, and ability to collaborate effectively as part of a team. 

Here are some interview questions to ask a mid-level PHP developer.

Explain the concept of PHP data objects and their importance in PHP development.

Data objects are an important concept in PHP, allowing developers to access and manipulate data from a database. This question will assess the candidate's technical knowledge and problem-solving skills. 

PHP data objects provide an object-oriented interface to access databases, making interacting and manipulating data easier. They are also beneficial because they provide a layer of abstraction between the code and the database, making it easier to maintain and manage.

How would you handle a situation where your PHP application needs to scale to accommodate heavy traffic?

This question will allow you to assess the candidate's understanding of scalability and ability to think independently. An ideal answer should include optimizing the current version of PHP code snippets and libraries, scaling up the infrastructure, using a caching layer to reduce load times, and utilizing asynchronous processing. Thorough answers should also include steps such as using a distributed architecture and employing cloud computing technologies.

Describe an instance where you used a PHP framework to improve the efficiency of a project. Which framework did you use and why?

Frameworks can be incredibly useful when improving the efficiency and scalability of a project. This question will allow you to assess the candidate's experience with various frameworks and how they can use them in a professional setting. A good answer should include an example of a project they worked on, the framework they used (for example, Laravel or Symfony), and why it was the best choice for the project. They should also be able to explain how the framework helped them complete the project quickly and efficiently.

What are some security concerns when developing with PHP, and how can you mitigate them?

Security is crucial for any web application, so it's important to understand the candidate's approach to this concept. The ideal answer should include using prepared statements with parameterized queries, sanitizing user input, and avoiding using eval() or exec(). They should also demonstrate an understanding of encryption techniques and protocols, such as SSL/TLS.

Senior-Level PHP Developer Interview Questions 

When interviewing for a senior-level PHP developer position, you should focus on understanding the candidate's extensive experience, deep knowledge of PHP variables, PHP files, PHP functions, and ability to lead and manage teams effectively. At this level, you're looking for strategic thinkers who can design complex systems, solve challenging problems, and make high-level decisions that can significantly impact the direction of your projects. Candidates' willingness to stay updated with the latest trends in PHP development and their ability to mentor junior developers are also key factors to consider. 

Here are some senior-level PHP developer interview questions you can ask.

How do you keep up-to-date with the latest advancements in PHP and related technologies? 

At this level, you need a candidate who’s committed to professional development and is willing to stay up-to-date with the latest trends in PHP development. A candidate could mention using various learning platforms, attending conferences or webinars, and subscribing to relevant newsletters.

How would you handle a junior developer struggling with a PHP task?

Leadership and communication skills are essential for any senior-level developer. This question will allow you to assess the candidate's ability to mentor junior developers. An ideal answer should include breaking the task into smaller parts, guiding the developer through the steps, and providing feedback. Bonus points should be awarded if the candidate can give an example from their own experience.

Discuss a time when you had to make a high-level decision during a project. What factors did you consider, and what was the outcome?

Senior-level positions require strategic thinking and the ability to make decisions that can significantly impact a project. An ideal answer should demonstrate their capacity to analyze a situation, weigh the pros and cons, and make a decision in the project's best interest. The candidate should be able to explain the factors they considered, such as budget, timeline, and resources needed. They should also be able to discuss their decision and why they made it.

Hire PHP Developers With Revelo

Finding top PHP developers can be challenging even for the best hiring managers, especially when looking for candidates with specific skills. However, Revelo can simplify the process. 

We understand your challenges and offer a curated pool of highly skilled, English-proficient, and time-zone-aligned PHP developers who are flexible and ready to adapt to your company's needs. We also take the hassle out of administrative tasks by managing payroll, taxes, benefits administration, and compliance with local regulations, so you can focus on growing your business.

Our platform gives you access to top-tier talent and saves you valuable time and resources. With Revelo, you're not just hiring a developer but gaining a team member who can drive your projects forward. 

Contact Revelo to start your hiring journey with Revelo today.

Why Choose Revelo?

Quick turnaround for candidate shortlists

A vast talent pool of 
pre-vetted developers

Professional sourcing, vetting, and onboarding support

Hire Developers
Miguel G.
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6 years
Hire Developers

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