Nearly a fifth of professional developers surveyed in 2023 said they had used PHP that year, placing it among the top 10 programming languages with Python and Java, according to Stack Overflow. And PHP programmers are prolific: Nearly 80% of websites use PHP-based back ends, per W3Techs, bolstered in no small part by the massive popularity of private installations of WordPress—whose core and customizations are written using PHP.

Demand for PHP developers for hire remains steady as the language continues to evolve: Codebases using PHP need to be maintained in order to work with currently supported and secure PHP versions. With such a large submarket, it can be difficult for development companies and startups to attract top PHP developers, and even more difficult to efficiently assess a large number of candidates. This guide will help you do both by outlining subskills to watch for, interview questions to ask, and points to cover in a winning job description.

What Attributes Distinguish Quality PHP Developers From Others?

Before exploring distinguishing attributes, it helps to first answer the question, “What does a PHP developer do?” The responsibilities of a PHP developer include writing, testing, and maintaining the source code for server-side web apps. These web applications can be built using either pure PHP or by leveraging various PHP frameworks like Laravel, Symfony, CakePHP, Yii, Zend, and CodeIgniter; content management systems (CMS) like WordPress, Drupal, and Joomla!; or even e-commerce platforms such as Adobe Commerce, formerly Magento.

Deep skills with a particular PHP framework allow a programmer to multiply their productivity by avoiding the reinvention of the wheel. But familiarity with multiple frameworks allows PHP experts to make better-informed choices in the case of greenfield projects.

The best PHP programmers ensure PHP applications are performant and secure, avoid mistakes, and write code that follows well-thought-out application development principles. They will have experience with common back-end development tasks, like connecting to databases, and be capable of handling basic DevOps responsibilities, like creating and configuring environments. They will also know how to meet prudent security standards to avoid unnecessary business risks.

Factors to ensure that your potential hire produces high-quality code

Some of the aforementioned areas can be evaluated based on a candidate’s résumé and follow-up discussions. However, many companies elect to assess programming ability directly, either with a live coding interview or a take-home assessment.

Both of these strategies add to time requirements on both sides of the table, although companies can outsource these evaluations, particularly live coding interviews. But without some kind of code quality evaluation, companies cannot judge for themselves the quality of PHP code the candidate can be expected to produce once hired. One alternative for candidates who happen to be open-source contributors is for companies to directly evaluate their code contributions, but it’s much harder to produce consistent metrics with this tactic.

The consequences of not evaluating a candidate’s coding abilities may involve additional training expenses or a lost onboarding investment—assuming a company has a functioning quality assurance system that would catch newcomers’ mistakes before they did any serious harm to the product.

How Can You Identify the Ideal PHP Developer for You?

Hiring managers who understand the most common types of PHP projects are better positioned to spot appropriate candidates and match them to their business needs. Whether it’s within the scope of customizing a CMS or other type of website, experts in the PHP programming language are most commonly sought to:

• Build a dynamic site or add dynamic components, such as product listings, search, user registration, authentication, a shopping cart, and more.
• Integrate an existing site with other systems, such as third-party payment processing APIs.
• Troubleshoot and optimize poorly performing websites.
• Implement advanced security mechanisms, such as multifactor authentication, thorough input sanitization, secure session management, and industry-standard encryption protocols.
• Assess code for adherence to industry standards, proper structure, and security requirements.
• Test code across browsers, devices, and operating systems to ensure seamless functionality throughout the development process.
• Optimize code for different platforms to deliver a consistent user experience.

A preexisting project built upon a PHP framework or platform like WordPress could leverage the technical skills of a PHP specialist. In particular, experience with Symfony and Laravel is helpful because Symfony is the basis for other popular PHP-based technologies like Drupal, while Laravel has established itself as a fundamental framework for numerous existing products. In addition, Laravel is excellent for rapid prototyping, whereas Symfony provides a more stable foundation for longer-term scalability. But each PHP-based system has its nuances, so it’s worth checking a candidate’s years of experience in a specific skill if you want them to hit the ground running.

Beyond frameworks and platforms, several related technologies are strongly relevant when examining the experience of PHP developers for hire:

Additional complementary PHP developer skills

• HTML, CSS, and JavaScript — In many ways, PHP’s primary output mechanism is to generate HTML. Often, passing data via JSON to the JavaScript running on a page will be a useful skill even for a PHP specialist focused only on an app’s back end, but a full-stack developer will really need to know CSS and JavaScript—as well as related technologies such as Node.js and React.js—to complete their front-end development skill sets.
• Relational (SQL) databases like MySQL and PostgreSQL — While not the only approach to storing data on the back end, SQL is a well-established standard and still wholly appropriate for a plethora of use cases. Unless your tech stack specifically uses a NoSQL database like MongoDB, strong SQL skills are a must when vetting a PHP expert. It’s especially helpful if their experience aligns with the particular database your project uses.
• REST APIs and web servers — Your project may not implement its own REST API—perhaps using a GraphQL-based API instead—but chances are your project’s back end will eventually need to integrate with a third-party REST API. To that end, it’s worth hiring a PHP engineer who knows a few tricks about optimizing async calls to REST APIs and handling their errors appropriately.
• Object-oriented programming (OOP) and model-view-controller architecture — These widely used approaches to coding result in more readable, modular, and maintainable code. PHP developers not well versed in them may take longer to familiarize themselves with your project’s codebase and may struggle to create code others can collaborate on efficiently, lowering your return on investment. This is crucial not only for large-scale projects, but also for smaller ones because they can only evolve substantially if they have a cohesive architectural approach.
• Unit testing — Even the most basic software development project benefits from this automated testing technique. Having a suite of unit tests means that specific modules of code can be counted on to continue working correctly, even when seemingly unrelated code is changed. Insist on PHP experts who are serious about unit testing: Without it, it’s all too easy for developers to waste time in a vicious circle, fixing an urgent bug in a way that causes another one to resurface.

When employing dedicated PHP developers, it is important that they have the right mix of technical and communication skills. The latter is important because PHP experts usually work on complex core system features in which interaction with other team members—whether in-house or remote—is essential. Furthermore, organizational skills—including fluency in indispensable collaboration and source control tools like Git—should be considered a given for any PHP app development role.

How to Write a PHP Developer Job Description for Your Project

Before looking to hire the best PHP developers, it is necessary to define technical project requirements and scope. Writing down the specifics of your project will provide clarity on the skills gap you face, the gaps you anticipate down the road, and whether it would be better to focus on hiring a full-time employee or opt for the flexibility of a freelance PHP developer. When hiring remote PHP developers, make sure to list the time zones desired, making sure there are sufficient windows of time for team members to communicate. Specify your project management environment, as well as how new hires and freelancers are onboarded to your in-house team.

After defining your plan and any skills gap, your next task is to create a job post. It’s helpful to use a template for this and include the most relevant and attractive details about your organization, development team, and project.

What Are the Most Important PHP Developer Interview Questions?

When looking to hire PHP programmers, open-ended questions can be used to spark further discussion during the interview process:

• What PHP frameworks have you worked with, and what has your experience with each been like?
• Can you provide an example of a recent PHP project you have contributed to that makes you proud?
• How would you use PHP template engines to create dynamic content? Which template engines have you used, which do you prefer, and why?
• How would you go about using PHP to interact with a database to retrieve data?

But quiz-style questions can be revealing as well:

What is the difference between the isset and empty functions in PHP?

The isset function is used to determine if a variable exists and has a non-null value, returning true in that case. In contrast, the empty function checks if a variable is considered empty, returning true if the variable is empty (i.e., not set, false, 0, an empty string, an empty array, or null). While isset checks for existence and a non-null value, empty specifically focuses on emptiness, including null values.

How can you prevent SQL injection vulnerabilities in PHP?

Prepared statements or parameterized queries are used to prevent SQL injection vulnerabilities. Prepared statements separate the SQL code from the user input, eliminating the possibility of injecting malicious code. By binding the input values to placeholders in the SQL statement, the database engine can distinguish between the actual SQL code and user-supplied data, effectively preventing any unauthorized SQL operations.

How do you handle errors in PHP?

In PHP, errors and exceptions can be handled using error-handling mechanisms. One common approach is to use the try-catch block to catch exceptions gracefully. By wrapping the code that may generate an exception or error inside the try block, you can catch the specific instance and provide appropriate handling or recovery logic in the corresponding catch blocks.

What is the difference between include and require in PHP?

Both include and require are used to include and evaluate external PHP files. The main difference between them is how they handle errors. The include statement refers to a file and continues the script execution even if the file is not found, resulting in a warning. In contrast, the require statement refers to a file and stops the script execution with a fatal error if the file is not found or fails to be included. In situations where the included file is essential for the script’s functionality, require is often preferred to ensure that the script doesn’t proceed without it.

How does PHP handle sessions? Explain the process of initializing and using sessions in PHP.

PHP provides built-in support for handling sessions, which allows developers to persist data across multiple requests for the same user. The process of initializing and using sessions involves the following steps:

• Session initialization — To start a session in PHP, a developer needs to call the session_start function. This function creates a unique session ID and initializes a session file on the server to store session data.
• Storing and retrieving session data — After starting a session, data can be read and written using the $_SESSION superglobal array. For example, a developer can set a session variable like $_SESSION['username'] = 'John'; to store the username.
• Using session data — Throughout the user’s session, a developer can access the stored session data by referencing the corresponding session variable. For instance, they can display the username by echoing $_SESSION['username'];.
• Session destruction — When the session is no longer needed or when the user logs out, a developer can call session_destroy. This clears all session data and deletes the session file on the server.

Understanding how sessions work in PHP is essential for managing user authentication, personalizing output, and maintaining state across multiple requests.

Why Do Companies Hire PHP Developers?

PHP’s continued dominance of back-end web projects keeps its ecosystem thriving. Because PHP and its popular frameworks are not likely to die out any time soon, it often makes good business sense to hire developers offering development services with a focus on PHP to maintain an existing PHP codebase.

Companies continue to hire experienced PHP developers for greenfield development projects, too. The productivity boost and endless developer resources that come with choosing a PHP technology like WordPress, Drupal, Laravel, or Symfony are advantages that are hard to ignore. This not only makes PHP coders for hire more numerous, but also makes specializations worth paying attention to if your project is on a tight timeline.

For any use case, there’s at least one PHP-based framework or platform that will help a PHP expert expedite your project. Now that you know which secondary skills to seek, you’re in a much better position to match PHP engineer candidates to your business needs.

The technical content presented in this article was reviewed by Florin Cabuz.

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