How do I create a custom REST API endpoint in WordPress?

You create a custom REST API endpoint in WordPress using the `register_rest_route()` function in your theme's functions.php or a custom plugin. The basic structure involves specifying a route (e.g., `myplugin/v1/resources`), a callback function that processes the request and returns data, and optional permission callbacks. You'll also need to handle parameters and sanitise output. WordPress has excellent documentation on the REST API handbook to get you started.

What are the best hosting options for headless WordPress in the UK?

For headless WordPress, you're essentially using WordPress as an API, which means the hosting needs are different from a traditional WP site. Managed WordPress hosts like Kinsta, WP Engine, or Cloudways with UK data centres are strong choices. They offer robust caching, easy admin, and great performance for API requests. You can also use them alongside static hosting for the frontend, like Vercel or Netlify, to get the best of both worlds.

How do I ensure my custom REST API is GDPR compliant?

To make your custom REST API GDPR compliant, first conduct a data audit to identify what personal data your API collects and returns. Ensure you have legal bases for processing, and implement data minimisation – only expose what's necessary. Use secure authentication to prevent unauthorised access, and support user rights like data deletion via your API. Also, document your data flows and update your privacy policy to reflect the API's use, as required by the ICO in the UK.

Can I use headless WordPress with existing WordPress plugins?

Yes, many plugins work in a headless setup because they primarily operate in the admin dashboard. Plugins like Advanced Custom Fields, Yoast SEO, and WooCommerce (for headless e-commerce) work well. However, plugins that output frontend HTML directly, like page builders, become redundant. Always test each plugin to ensure it doesn't rely on theme template files. For some plugins, you may need to create custom REST endpoints to access their data, but most modern plugins offer REST API support natively.

WordPress Headless CMS: Building a Custom REST API in 2026

17 August 2026

Discover how to build a headless WordPress CMS with a custom REST API in 2026. UK-specific tips for performance, hosting, and security.

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What is Headless WordPress and Why Use a Custom REST API?

Headless WordPress separates the backend content management from the frontend presentation layer. Instead of a monolithic theme, you use the WordPress admin to manage content, then deliver it via the REST API to any device – a React site, a mobile app, or even a digital kiosk. A custom REST API goes beyond the default endpoints, letting you define exactly what data is exposed and in what format. For UK businesses, this means you can tailor content for local audiences, integrate with UK-specific services, and build faster, more secure experiences. Whether you're a publisher in London or an e-commerce brand in Manchester, a custom API gives you full control over your content architecture.

Setting Up Custom REST Endpoints for UK-Specific Content

Creating custom REST endpoints in WordPress is straightforward using the `register_rest_route` function. You can build endpoints that return curated content for specific UK regions, handle VAT calculation, or deliver store locations with opening times that match British high street expectations. For example, a retail chain with branches across the UK might create an endpoint like `/wp-json/custom/v1/stores?postcode=SW1` that returns stores within a radius, along with distance and local offers. Remember to sanitise and validate all inputs, especially when handling postcodes or addresses. This approach keeps your API lean and efficient, avoiding the overhead of pulling in unrelated WordPress data while ensuring your frontend gets exactly what it needs.

Authentication and Security: GDPR and Data Protection

Security is paramount when exposing a custom REST API, particularly in the UK where GDPR fines can be substantial. Use authentication methods like OAuth 2.0 or JWT tokens to control who can access your endpoints. For public endpoints, ensure you never leak sensitive data such as user emails or unpublished content. Implement rate limiting to prevent abuse and use HTTPS across all communications. Also, respect UK data protection laws by allowing users to request data deletion and by anonymising any personal data you collect. If you're using cookies or tracking, you'll need a clear consent mechanism. Regular security audits of your custom endpoints help you stay compliant and keep your British customers' trust.

Performance Optimisation: Hosting and Caching for UK Audiences

A headless setup can be incredibly fast, but only if you optimise your WordPress hosting and API delivery. For UK audiences, choose a hosting provider with data centres in the UK or use a CDN like Cloudflare to cache your REST API responses at edge locations across Britain. This reduces latency for users in Edinburgh, Cardiff, and London alike. Use object caching (like Redis) to speed up server-side queries, and consider creating static snapshots of your API for high-traffic pages. You can also use browser caching headers to store repeated requests. Monitor your API response times with tools like GTmetrix or Lighthouse and aim for sub-200ms responses to keep both Google and your visitors happy.

Practical Example: Building a Trusted UK Store Locator Endpoint

Let's create a custom endpoint for a UK-wide grocery chain. First, register the route in your plugin: `register_rest_route('custom/v1', '/stores', ...)`. Inside the callback, query posts from a custom post type 'store' and use the Advanced Custom Fields plugin to expose hold the latitude and longitude. You can then accept a postcode parameter, geocode it using Google Maps or Postcodes.io (a free UK service), and return the nearest three stores ordered by distance. The response could include the store name, address, opening hours, and distances in miles. Here's a simplified snippet: `$request->get_param('postcode')` followed by a loop. This gives you a robust, location-aware feature that runs beautifully on a headless frontend, perfect for mobile users on the go.

FAQ

Yes, absolutely. Headless WordPress allows small UK businesses to deliver lightning-fast content without paying for expensive custom development. You can use WordPress as the admin dashboard and build a simple static site as the frontend. This is ideal for portfolio sites, local restaurants, or e-commerce stores that want to provide a seamless experience while keeping costs down. Just ensure you have the technical ability to maintain a separate frontend or consider using a service like Vercel or Netlify.

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