When developing a WordPress website, you often need to send and receive data asynchronously without reloading the page. Two primary technologies enable this functionality: REST API and AJAX. While both serve a similar purpose, they differ in their approach, implementation, and best use cases. In this article, we will compare REST API and AJAX in WordPress, highlighting their differences and guiding you on which one to use for your project. What is AJAX in WordPress? AJAX (Asynchronous JavaScript and XML) allows web pages to update dynamically by sending requests to the server in the background. In WordPress, AJAX is commonly used for tasks such as: How AJAX Works in WordPress WordPress provides a built-in AJAX handler using the admin-ajax.php file. When an AJAX request is made, it sends data to this file, which processes the request using a custom PHP function hooked to wp_ajax_{action} for logged-in users and wp_ajax_nopriv_{action} for non-logged-in users. Example of a basic AJAX call in WordPress: What is the REST API in WordPress? The WordPress REST API is a modern way to interact with WordPress using JSON-based HTTP requests. It allows developers to retrieve, create, update, and delete content programmatically, making WordPress more flexible as a headless CMS. How REST API Works in WordPress The REST API uses endpoints (URLs) to interact with WordPress data. The default WordPress API provides various endpoints, such as: Key Differences Between REST API and AJAX Feature REST API AJAX Communication Format JSON Form-encoded data or JSON Request Handling Uses HTTP methods (GET, POST, PUT, DELETE) Uses WordPress admin-ajax.php Authentication OAuth, Application Passwords, Cookie Authentication Slower due to admin-ajax.php overhead Performance Faster for API-driven sites WordPress themes and plugins Use Case Headless WordPress, mobile apps, external applications WordPress themes and plugins Which One Should You Use? Use REST API If: Use AJAX If:
