How to Interview a PHP Developer and What to Look For?

Vyom Srivastava
Vyom Srivastava
Published: 20.03.2021

So you’ve found suitable PHP developers and, you’re impressed by their profile and portfolio - now what? You schedule an interview with them to get to know more about them. The interview is one of the most important steps while hiring a PHP developer. It lets you find their capabilities and check if they’ll fit in your team or not.

Therefore, you can’t just throw a bunch of questions and expect the developer to meet your expectations. A perfect interview will always give you fruitful results in terms of revenue as well as client satisfaction. That’s why it’s important to make sure you ask the right strategic questions to your PHP developer candidates.

The interview process can be a lengthy and time-consuming task but when you put in the time, you can expect the PHP developer to meet all your requirements.

Let’s take a look and what you need to know about the interview process, and what you should ask prospective candidates - and remember, if you need help selecting the right company, tell us what you need. We can do the work for you and connect you with up to 5 companies within 72h that match your need- all for free.

Get to know the PHP developer

This is the first step when you’re interviewing PHP developers. First, let your candidate know a little about the company and what you do, and then move onto finding out about them. This conversation will set a base for the interview as the PHP developer will be sharing information that’s not on their resume.

Go through their portfolio and ask questions related to it. For example, if their portfolio shows that they have experience working on e-commerce websites, you can go through them and understand precisely what their role was as a developer on those projects.

Move on to the techie stuff

You can now start with basic tech questions related to the PHP language. This will give you an idea of how much the PHP developer is aware of the basic concepts. You may think that if a PHP developer knows the advanced concepts then they also have their basics covered - but it’s important not to ignore the basics in the interview.

Some of the questions that you can ask to test their understanding:

  • What is an array?
  • How many data types does PHP have?
  • What are some of the most basic PHP array and string functions?
  • How many types of loops are there in PHP?
  • How familiar are you with Object-Oriented Programming?

A PHP developer should be able to answer all these basic questions. If they can’t answer any of them then it’s a red flag for you. When trying to make sure you hire the best team, if you need help selecting the right company, tell us what you need. We can do the work for you and connect you with up to 5 companies within 72h that match your need- all for free.

So you’ve found suitable PHP developers and, you’re impressed by their profile and portfolio - now what? You schedule an interview with them to get to know more about them. The interview is one of the most important steps while hiring a PHP developer

Assess their problem-solving skills

This has to be the topmost priority for a PHP developer. Every PHP project comes with a lot of logical problems and solving these problems in a very optimised way makes the PHP application much faster.

You can pick projects from their portfolios and ask specific questions as to their approach to problem-solving, including how much time they take to solve, and in how many ways they can solve the same problem.

This will give you an idea about their problem-solving skills - an aptitude of critical importance, which will be essential throughout the project development.

Do they have a strong knowledge of database languages?

Every PHP web application generates or gathers some data. It can be user data for storing their passwords, images, and addresses or internal data like anything related to management. To store all of the data you need a database.

A PHP developer has to know at least one database language in order to store this data. One of the most popular databases which work perfectly with PHP is MySQL, and almost all PHP developers know how to write MySQL queries.

During the interview, you should ask questions about their experiences with databases to assess their proficiency. Always remember one thing that a PHP application without a database is just like a computer without a hard drive. You can do all the calculations but you can’t store the results. A PHP developer should know MySQL as a standard database.

Some of the questions that you can ask:

  • What is a database?
  • What is MySQL?
  • What are some different types of keys in MySQL?
  • Do you know other databases as well, like MongoDB?
  • What are the differences between SQL and NoSQL databases?
  • How many types of JOIN are there in MySQL?
  • What are foreign keys?
  • Write a SQL query to make JOIN between two tables?

These are just basic questions, you can introduce more and more complexity depending on the experience of the PHP developer.

Do they play with other frameworks?

Gone are the days when core PHP was only used to develop a PHP website. Now, there are a lot of PHP frameworks out there on the internet which can be used to speed up the development process.

The PHP frameworks come with a lot of advantages as well, such as:

  • Speeding up the development process.
  • Improving the performance of the application by introducing caching, templating systems, DRY, etc.
  • Making the code very easy to understand and is written in a structured way.

The PHP developer should know and understand the trending PHP frameworks and you can also ask them which is their favorite PHP framework and why.

If they’ve used any PHP framework in their previous projects, be sure to ask them why they preferred that framework.

Some of the questions that you can ask:

  • Can you name some PHP frameworks that you have used in your previous projects?
  • Which is your favorite PHP framework and why?
  • What is MVC?
  • What are some popular PHP frameworks that you haven’t used?
  • What is the Zend engine?
  • What are Models?
  • What is View?
  • What are Controllers?
  • What are helper functions?

If they have used PHP frameworks, they should be able to answer these questions very easily.

Test their coding skills

Another important skill that a PHP developer should have is coding and its approach. They need to perform well in this test. You can give them some short and simple PHP programming questions and ask them to write the code.

This will save a lot of time as it’ll help you to understand how well the PHP developer knows the PHP language and how fast they can code. Coding a complete PHP project is a time-consuming process but writing down small-small functions on some of the most basic problems shouldn’t take much time.

Asking theoretical questions won’t give you a good understanding of their coding skills because anyone can just find the answers online and repeat them back to you in the interview. But there’s no substitute for real-time coding.

As a hiring manager, you’ll learn more about how well the candidate can write the PHP code. In the process, you’ll have to check the below points:

  • How fast can they code?
  • How clean and easy to understand the code is?
  • How are they writing the comments?
  • How much do they follow the best practices of coding?

You can give them one or two of the below questions:

  • Write a program in PHP to make the database connection and fetch the last 10 records from a table
  • Write a program in PHP to write a CSV
  • Write a program in PHP to upload a file on the server
  • Write a program in PHP to read a CSV and insert each row in the database

Test their familiarity with API development and 3rd Party API integrations

API development is very uncommon for PHP development. But this can be very beneficial for a PHP project where the data needs to be sent to different platforms.

It could also be beneficial for a PHP developer to know how to integrate third-party APIs, as many PHP applications involve several API integrations. For example, you may need to integrate a payment gateway in the PHP project, or include the social logins, or even to fetch the data from a completely different platform you’ll need to integrate the API.

So, the PHP developer should know how to make API calls and fetch the data from the API. You can ask the below questions:

  • What is cURL?
  • What is REST API?
  • What are the different methods in API?
  • How to make a GET and POST request in PHP?
  • What are the different API you have integrated using PHP?
  • What is the difference between SDK and API?

Obviously, they don’t need to have experience integrating all the APIs available on the internet but you can expect them to have integrated at one API in each category like payment gateway, social logins, or geolocation. Some examples they might have worked with include Google login API, PayPal API, and Google Maps API.

So you’ve found suitable PHP developers and, you’re impressed by their profile and portfolio - now what? You schedule an interview with them to get to know more about them. The interview is one of the most important steps while hiring a PHP developer

Do they have a hunger to learn more?

A lot of companies face the problem that their developers don’t want to learn new tools and are reluctant to move past the same legacy languages they began their careers with. You would not want to be one of these companies that is forced to lay off their programmers.

You may want to avoid hiring someone who doesn't want to learn anything new and spends all their time on the legacy code since this will bring down the performance of the PHP application and at one point the server itself will stop supporting the legacy code.

Unfortunately, there’s no sure set of questions you can ask to test the candidate’s drive, enthusiasm, and hunger - rather, you’ll have to try to assess that through the person’s personality. Additionally, a company culture that promotes creativity and experimentation, as well as the nurturing of human capital, can go a long way to maintain and even heighten your new hire’s initial motivation.

Some points that you might want to look for in the PHP developer are:

  • How descriptive are the comments? Yes, comments in the code tell a lot about the personality of the PHP developer. If the comments can be easily understood even by a non-technical person then it’s a positive sign.
  • How frequently does the developer check out the newly released features?
  • How many PHP blogs are they following?
  • Do they know what’s trending in the PHP market?
  • Are they trying anything new using PHP?

Do they have additional technical skills?

This depends on your requirements. Do you want the PHP developer to work on the frontend or not, and do you want to explore other technologies or not?

A lot of developers learn about new tech stuff, and additional skills can always be an asset to your company. Keep an eye out for these additional skills on the resume, and for example, if the PHP developer also knows about AngularJS then ask questions related to it.

PHP developer interview questions

What are the advantages of using Object Oriented Programming in PHP?

You should expect to get all the features of OOP like objects, classes, and so on.

What was the most difficult challenge you’ve faced as a PHP developer?

Every PHP developer faces some unique challenges in every PHP project. You can ask them how they solved the problem and is there any other way of doing the same task?

How do you plan a PHP project?

This is a very interesting question and you can expect different answers from different PHP developers. Some developers start from the database point of view while some developers start from the PHP part.

Do you use version-controlling software?

To maintain a PHP project, version control is very important and the PHP developer should have proper knowledge of at least one version controlling software like SVN or Git.

Get ready to find your perfect PHP developer

We’ve covered almost all the points that you should look for in a PHP developer. It can be time-consuming to find the right PHP developer for your company and project, but if you follow these steps, you should stand a chance of finding the ideal fit.

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