WordPress Developer Interview Questions Guide: 30 Questions to Ask Before You Hire

How to use these WordPress developer interview questions

A good WordPress developer interview checks three things: whether the developer understands how WordPress works, whether they can do the work your site needs, and whether they work safely on a live website. The questions below are grouped in that order. Each one includes what a good answer should cover, letting you judge the reply even if you are not a developer yourself.

You do not need to ask all 30. Pick five or six from each group that match your project, and add the level-specific questions for the experience you are hiring for.

WordPress basics: questions for every candidate

1. What is the difference between WordPress.org and WordPress.com?

A good answer covers: WordPress.org is the free, self-hosted software that gives full control over themes, plugins, and code. WordPress.com is a hosted service run by Automattic, with plan-based limits on plugins and custom code. A developer should know which one your site runs on and what that allows.

2. What is the difference between a theme and a plugin?

A good answer covers: a theme controls how the site looks, and a plugin adds or changes functionality. Features that must survive a theme change, such as custom post types or business logic, belong in a plugin, not the theme.

3. What is a child theme, and when should you use one?

A good answer covers: a child theme inherits the parent theme and holds your custom changes. Updates to the parent theme then do not overwrite your customisations. A developer who edits the parent theme directly will lose work at the next update.

4. What is the difference between posts and pages?

A good answer covers: posts are time-based content shown in feeds and archives, with categories and tags. Pages are standalone content, such as About or Contact, without dates or tags. The answer is basic, but a hesitant reply is a warning sign.

5. What is the WordPress Loop?

A good answer covers: the Loop is the PHP code WordPress uses to fetch and display posts on a page. A strong candidate can also explain when to use a custom query, such as WP_Query, instead of changing the main query.

6. Is PHP used in WordPress, and how much do you work with it?

A good answer covers: yes. WordPress core, themes, and plugins are written mainly in PHP, with JavaScript for blocks and interactive features, and MySQL or MariaDB for the database. A developer who cannot read or write PHP is a site builder, not a developer.

Technical WordPress developer interview questions

7. What are hooks, and what is the difference between actions and filters?

A good answer covers: hooks let developers change WordPress without editing core files. Actions run code at a specific point, for example when a post is saved. Filters change data before it is used or displayed, for example editing a post title. Expect mentions of add_action and add_filter.

8. How do you create a custom post type and a custom taxonomy?

A good answer covers: custom post types are registered with register_post_type and taxonomies with register_taxonomy, usually inside a plugin. The developer should mention labels, URL slugs, and flushing permalinks after registration.

9. How would you build a custom plugin instead of using an existing one?

A good answer covers: they check the plugin directory first, and only build custom when no reliable plugin fits, an existing plugin is too heavy, or the feature is unique to the business. A good developer weighs maintenance cost, not just build cost.

10. Do deactivated plugins slow down WordPress?

A good answer covers: deactivated plugins do not run, and they do not slow the site in normal use. They can still be a security risk if they contain vulnerable files, and unused plugins should be deleted rather than left deactivated.

11. What are wp-config.php and .htaccess used for?

A good answer covers: wp-config.php holds the database connection, security keys, table prefix, and settings such as WP_DEBUG. On Apache servers, .htaccess controls permalinks, redirects, and some security rules. A strong candidate knows never to expose either file publicly.

12. How many database tables does WordPress create, and how do you change the table prefix?

A good answer covers: a standard single-site install creates 12 core tables, such as wp_posts and wp_options. The prefix is set in wp-config.php, and changing it on a live site also needs the database tables and some option values renamed. The answer shows how well they understand the database.

13. How do you work with the block editor and block themes?

A good answer covers: experience building custom blocks or block patterns, using theme.json for global styles, and knowing when a classic theme is still the better choice for an existing site.

14. Have you used the WordPress REST API?

A good answer covers: the REST API lets WordPress send and receive data as JSON, for headless front ends, mobile apps, and integrations. Look for a real example, such as connecting a CRM or building a custom endpoint.

15. How much WooCommerce experience do you have?

A good answer covers: product setup, payment gateways, shipping rules, and customising templates through hooks rather than editing core plugin files. For a store project, ask how they would handle a checkout problem on a live shop. See WooCommerce developers on Osdire for typical project types.

Security and performance questions

16. How do you secure a WordPress website?

A good answer covers: keeping core, themes, and plugins updated, strong passwords and two-factor login, limited admin accounts, a security plugin or firewall, regular off-site backups, and secure hosting. In custom code, expect mentions of nonces, sanitising input, escaping output, and $wpdb->prepare for database queries.

17. What would you do if a WordPress site were hacked?

A good answer covers: a calm, ordered process: take a backup of the current state, put the site in maintenance mode, scan and remove malicious files, replace core files, check users and database entries, change every password and security key, update everything, and find how the attacker got in.

18. How do you make a slow WordPress site faster?

A good answer covers: measuring first with tools such as PageSpeed Insights, then fixing the causes: heavy plugins, unoptimised images, no caching, render-blocking scripts, and slow hosting. A strong candidate mentions Core Web Vitals and does not promise a score before seeing the site.

19. How do you update WordPress safely?

A good answer covers: taking a full backup, testing updates on a staging site first, updating plugins and themes in a planned order, and checking key pages and forms afterwards. A developer who updates everything on the live site at once is taking a risk with your business.

Process and communication questions

These matter as much as technical skill, especially when you hire a freelance or remote WordPress developer.

20. Do you work on a staging site or directly on the live site?

A good answer covers: all meaningful changes are built and tested on staging, then pushed to live. Small text edits may happen on live, but never code or plugin changes without a backup.

21. How do you take over a website another developer built?

A good answer covers: an audit before any change: theme and plugin list, custom code, hosting, backups, and known issues. They should flag risks and agree on priorities before touching anything.

22. How do you estimate time and cost for a project?

A good answer covers: breaking the work into tasks, asking questions about unclear requirements, and giving a fixed price for a defined scope or an hourly estimate with a cap. Vague answers often lead to surprise bills. For typical prices, see our WordPress developer cost guide.

23. How will you keep me updated during the project?

A good answer covers: a set update rhythm, such as a short weekly summary, a clear point of contact, and how they share work for review.

24. What happens after launch?

A good answer covers: a short support period for bugs, a handover of logins and documentation, and an offer of ongoing maintenance if you need it.

25. Who owns the code and the website when the project ends?

A good answer covers: you own the site, the content, and the custom code you paid for, with all admin, hosting, and domain access in your name. Licences for premium themes and plugins should be registered to you, not the developer.

WordPress interview questions by experience level

Questions for junior developers and freshers

Junior WordPress developers, usually with up to two years of experience, should handle setup, content, theme settings, and plugin configuration. Focus on basics and attitude:

• 26. Walk me through installing WordPress and setting up a theme. A good answer covers hosting, database creation, installation, permalinks, and basic security settings.
• 27. How do you find the cause when a plugin breaks a page? A good answer covers turning on debugging, deactivating plugins one by one on staging, and checking the browser console.

Questions for mid-level developers (around 3 to 5 years)

Mid-level developers should build custom themes, use hooks confidently, and work with WooCommerce and performance. The technical questions above, especially 7 to 18, fit this level.

• 28. Show me a custom theme or plugin you built and explain one decision you made. A good answer explains a trade-off, not just the features.

Questions for senior developers (5 to 10+ years)

Senior WordPress developers should design solutions, review other people's code, and handle complex sites:

• 29. How would you structure a large WordPress site with custom data and integrations? A good answer covers custom post types, plugin architecture, caching, deployment, and version control with Git.
• 30. How do you review code and deploy changes safely? A good answer covers code review, coding standards, automated or manual testing, and a repeatable deployment process.

Red flags in a WordPress developer interview

• No staging or backup process. Changes go straight to your live site.
• Edits theme or core files directly. Updates will wipe the work or break the site.
• Cannot show recent, live work. Ask for links, not only screenshots.
• Promises guaranteed speed scores or rankings. Results depend on the site, hosting, and content.
• Vague pricing. No breakdown, no scope, or a price far below every other quote.
• Wants to keep admin, hosting, or domain access in their name. You should always own your accounts.
• Answers every problem with another plugin. Too many plugins slow sites down and add risk.

For more warning signs across web projects, see red flags when hiring a web developer.

How to score a WordPress developer's answers

Score each answer from 1 to 3 to compare candidates fairly:

Weight the questions that matter most for your project. A WooCommerce store should weight questions 15 to 19, while a content site might weight 2, 3, 13, and 18.

Give a short paid test task

Interview answers show knowledge. A small, paid test task shows how the developer actually works. Good WordPress test tasks take two to four hours, for example:

• Building one custom block or page template from a design
• Fixing a known bug on a staging copy of your site
• Writing a small plugin that adds one custom post type

Judge the result on code quality, communication, and whether they asked sensible questions, not only on speed. For a ready list of general pre-hire questions, see 10 questions to ask before hiring a web developer.

Interviewing WordPress developers on Osdire

On Osdire, you can browse WordPress developers, message them before you order, and ask any of the questions above. You can also post a project, compare the offers you receive, and interview your shortlist. Your payment is held securely by Osdire and released to the developer only after you approve the work.