Exposing Your API in Drupal: A Beginner’s Guide

on 28 September, 2025

APIs (Application Programming Interfaces) have become the backbone of modern digital experiences. Whether you’re building a mobile app, connecting with third-party services, or creating a headless CMS, exposing APIs allows seamless data exchange between platforms.

Drupal, a powerful open-source CMS, isn’t just about content management. It’s also an excellent framework for API-first website development. With its built-in tools and modules, Drupal makes it easy for beginners and professionals alike to expose APIs securely and efficiently.

In this guide, we’ll walk through the fundamentals of exposing your API in Drupal, explain best practices, share practical examples, and highlight how a Drupal development agency or a skilled Drupal company can help you scale.

What Exactly Is an API and Why Do You Need One?

Before we dive into the "how," let's clarify the "what" and "why." An API acts as a messenger, allowing different software applications to communicate with each other. Imagine a waiter in a restaurant: you (the application) tell the waiter (the API) what you want from the kitchen (the server/database), and the waiter brings it back to you. You don't need to know how the food is cooked, just how to order it.

In the context of Drupal website development, an API allows other applications to request and receive data from your Drupal site in a structured format, typically JSON or XML. This opens up a world of possibilities:

Mobile Applications: Powering native iOS or Android apps with content directly from your Drupal backend.
Decoupled Architectures: Building a sleek JavaScript frontend (e.g., React, Vue, Angular) that consumes data from a headless Drupal backend.
Third-Party Integrations: Connecting your Drupal site with CRMs, marketing automation tools, e-commerce platforms, or other external services.
Content Syndication: Distributing your content to multiple external platforms automatically.
Internet of Things (IoT): Providing data for smart devices and sensors.

For any Drupal company looking to stay competitive, understanding and implementing APIs is no longer an optional extra; it's a core competency.

Drupal's Built-in API Capabilities: A Strong Foundation

One of Drupal's many strengths lies in its robust architecture, which inherently supports API exposure. From its earliest versions, Drupal has been designed with modularity and extensibility in mind, making it an excellent platform for serving data.

Initially, developers often relied on contributed modules like Services for creating RESTful APIs. While incredibly powerful, Services sometimes required a steeper learning curve. However, with Drupal 8 and beyond, significant strides have been made to integrate API capabilities directly into Drupal core.

The introduction of the RESTful Web Services and Serialization modules in Drupal core revolutionized how developers approach API exposure. These modules provide a powerful and flexible foundation for creating REST APIs without needing additional contributed modules for basic functionality. This means if you're engaging in modern Drupal website development, much of what you need is already at your fingertips.

Getting Started: Enabling Core API Modules

To begin exposing your API in Drupal, you'll first need to ensure the necessary core modules are enabled. This is a straightforward process:

Access your Drupal site as an administrator.
Navigate to Extend (or admin/modules).
Locate and enable the following modules:
- RESTful Web Services: Provides the core REST functionality.
- Serialization: Handles the conversion of Drupal data into formats like JSON or XML.
- HAL (Hypertext Application Language): (Optional but recommended) Provides a standardized way to represent resources and their relationships in a REST API, enhancing discoverability.
- Basic Auth: (Optional, for simple authentication) Allows clients to authenticate using HTTP Basic authentication (username/password). For more robust authentication, consider OAuth or JWT.

Once these modules are enabled, you've laid the groundwork for your API.

Understanding REST Principles: The API's Language

Before you start creating endpoints, it's crucial to grasp the fundamental principles of REST (Representational State Transfer). REST is an architectural style for designing networked applications, emphasizing statelessness, client-server separation, and a uniform interface.

Key REST concepts include:

Resources: Any data object that can be accessed via the API (e.g., a node, a user, a taxonomy term). Each resource has a unique identifier (URL).
HTTP Methods: Standardized verbs used to perform actions on resources:
- GET: Retrieve a resource.
- POST: Create a new resource.
- PUT: Update an existing resource (replaces the entire resource).
- PATCH: Update an existing resource (applies partial modifications).
- DELETE: Remove a resource.
Statelessness: Each request from a client to the server must contain all the information needed to understand the request. The server should not store any client context between requests.
Representations: Resources are represented in various formats (e.g., JSON, XML) for clients.

Adhering to REST principles makes your API predictable, scalable, and easy for other developers to consume. This is a critical consideration for any Drupal development agency aiming for long-term maintainability.

Exposing Content Entities: Your First API Endpoints

Drupal's core API modules make it incredibly simple to expose content entities (nodes, taxonomy terms, users, etc.) as RESTful resources. Let's walk through an example of exposing "Article" content type nodes.

Step 1: Configure REST Resource Settings

Navigate to Configuration > Web services > REST UI (admin/config/services/rest). This is a contributed module that simplifies configuring REST endpoints visually. While not core, it's highly recommended for ease of use. If you don't have it, install and enable the "REST UI" module.
On the REST UI page, you'll see a list of available content entity types.
Find the "Content" entity type and click "Enable" or "Edit" next to it.
Here, you'll configure the settings for your content entities:
- Path: This is the base URL for your content entity. A common choice is /node/{id}.
- Formats: Select the data formats you want your API to support (e.g., json, xml, hal_json). json and hal_json are often preferred for modern web development.
- Authentication Providers: Choose how clients will authenticate. For a public API, "Anonymous" might suffice (though not recommended for sensitive data). For authenticated access, basic_auth or cookie are options, but oauth2 (via contributed modules) is generally more secure for third-party applications.
- Methods: Select the HTTP methods you want to allow (e.g., GET for retrieval, POST for creation, PATCH for updates, DELETE for removal). For simply exposing content, GET is usually sufficient initially.
For exposing Article nodes, you might set:
- Path: /api/articles (or /node if you want all node types)
- Formats: json, hal_json
- Authentication: anonymous (for read-only public access)
- Methods: GET
Save the configuration.

Step 2: Grant Permissions

Even with the REST endpoint configured, users (including anonymous users) need permission to access the data.

Navigate to People > Permissions (admin/people/permissions).
Scroll down to the "RESTful Web Services" section.
Grant the "Access GET on Content resource" permission to the appropriate roles (e.g., "Anonymous user" for public read access).
Grant "Access GET on any content entity" for more generic access to all content types. You might also want to grant "View published content" under Node permissions.

Step 3: Test Your API Endpoint

Now that your API is configured and permissions are set, it's time to test!

Ensure you have some content (e.g., an Article node) published on your Drupal site.
Open your web browser or a tool like Postman/Insomnia.
Navigate to your API endpoint.
- To get a list of all nodes: your-drupal-site.com/node?_format=json
- To get a specific node (e.g., node ID 1): your-drupal-site.com/node/1?_format=json
- If you configured a custom path like /api/articles, you would use your-drupal-site.com/api/articles/1?_format=json.

You should see a JSON representation of your content! This is a significant step in Drupal website development, as it means your data is now accessible programmatically.

Advanced API Exposure: Beyond Core Entities

While core entity exposure is excellent, your Drupal development agency might need more customized API endpoints. This is where custom module development comes into play.

Custom REST Resources with Drupal Modules

For highly specific data or business logic that doesn't directly map to a Drupal content entity, you can create custom REST resources using a custom module. This involves:

Defining the Custom Resource Plugin: You'll create a class that extends \Drupal\rest\Plugin\ResourceBase. This class defines the path, methods (GET, POST, etc.), and the logic for how data is retrieved, created, or updated.
Implementing HTTP Method Callbacks: Within your resource plugin, you'll implement methods like get(), post(), patch(), and delete() to handle the corresponding HTTP requests.
Defining Permissions: You'll need to define custom permissions for your new resource, similar to how you manage content entity permissions.

This approach offers maximum flexibility and is essential when you need to expose aggregated data, perform complex calculations, or integrate with external services before sending data back to the client. If you hire a Drupal developer for complex integrations, they will undoubtedly leverage custom REST resources.

Here's a simplified conceptual example of a custom REST resource module structure:

my_custom_api/
├── my_custom_api.info.yml
├── my_custom_api.module
└── src/
    └── Plugin/
        └── rest/
            └── resource/
                └── MyCustomResource.php

In MyCustomResource.php, you'd define your logic:

<?php

namespace Drupal\my_custom_api\Plugin\rest\resource;

use Drupal\rest\Plugin\ResourceBase;
use Drupal\rest\ResourceResponse;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Psr\Log\LoggerInterface;
use Drupal\Core\Session\AccountProxyInterface;

/**
 * Provides a 'MyCustomResource' REST Resource.
 *
 * @RestResource(
 * id = "my_custom_resource",
 * label = @Translation("My Custom Resource"),
 * uri_paths = {
 * "canonical" = "/api/custom-data/{id}"
 * }
 * )
 */
class MyCustomResource extends ResourceBase {

  /**
   * Constructs a new MyCustomResource object.
   *
   * @param array $configuration
   * A configuration array containing information about the plugin instance.
   * @param string $plugin_id
   * The plugin_id for the plugin instance.
   * @param mixed $plugin_definition
   * The plugin implementation definition.
   * @param array $serializer_formats
   * The available serialization formats.
   * @param \Psr\Log\LoggerInterface $logger
   * A logger instance.
   * @param \Drupal\Core\Session\AccountProxyInterface $current_user
   * The current user.
   */
  public function __construct(
    array $configuration,
    $plugin_id,
    $plugin_definition,
    array $serializer_formats,
    LoggerInterface $logger,
    AccountProxyInterface $current_user
  ) {
    parent::__construct($configuration, $plugin_id, $plugin_definition, $serializer_formats, $logger);
    $this->currentUser = $current_user;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static(
      $configuration,
      $plugin_id,
      $plugin_definition,
      $container->getParameter('serializer.formats'),
      $container->get('logger.factory')->get('my_custom_api'),
      $container->get('current.user')
    );
  }

  /**
   * Responds to GET requests.
   *
   * @param int $id
   * The ID of the item to retrieve.
   *
   * @return \Drupal\rest\ResourceResponse
   * The HTTP response object.
   *
   * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
   * Throws access denied exception if user has no permission.
   */
  public function get($id) {
    // Check permissions.
    if (!$this->currentUser->hasPermission('access custom api resource')) {
      throw new AccessDeniedHttpException('Access denied to custom API resource.');
    }

    // Replace with your actual data retrieval logic.
    // For example, fetch data from a custom database table or an external service.
    $data = [
      'id' => $id,
      'name' => 'Custom Item ' . $id,
      'description' => 'This is custom data for item ' . $id . ' from your Drupal site.',
    ];

    return new ResourceResponse($data, 200);
  }

  /**
   * {@inheritdoc}
   */
  protected function getBaseRoute($canonical_path = NULL, $method = 'GET') {
    // Override to enforce specific route access (e.g., using _access_rest_resources permission).
    return parent::getBaseRoute($canonical_path, $method);
  }

  // Define permissions in my_custom_api.permissions.yml
  // 'access custom api resource':
  //   title: 'Access custom API resource'
}

This snippet provides a skeleton; real-world implementation would involve more complex data handling and validation.

Views REST Export: A Powerful No-Code API Tool

For many scenarios, especially when exposing lists of content with specific filtering, sorting, or contextual arguments, the Views module (which is also in Drupal core) combined with its REST Export display offers an incredibly powerful, no-code solution. This is a game-changer for speeding up Drupal website development and a key tool for any experienced Drupal developer.

Here’s how to use it:

Create a New View: Go to Structure > Views (admin/structure/views) and click "Add new view."
Configure Basic View Settings:
- Give your view a name (e.g., "Recent Articles API").
- Show "Content" of type "Article" (or whatever you need).
- Crucially, do NOT create a page or block display initially.
Add a REST Export Display:
- Once the view is created, click the "Add" dropdown next to "Page" or "Block" and select "REST Export."
Configure the REST Export Display:
- Path: Set the API endpoint path (e.g., /api/v1/articles-list).
- Format: Change from "Serializer" to "JSON" or "HAL JSON."
- Fields: Add the specific fields you want to expose (e.g., Title, Body, Image, Author, Publication Date). You can rewrite field outputs and exclude them from display if needed.
- Filters: Apply any filters (e.g., "Published = Yes," "Content type = Article").
- Sort Criteria: Define how the results should be ordered (e.g., "Post date (desc)").
- Pager: Configure how many items per page and if an offset is allowed.
- Access: Set the permission required to access this API endpoint. You can use "Permission" and select "Access content" or a more specific custom permission.
Save the View.
Test Your Endpoint: Visit your-drupal-site.com/api/v1/articles-list (or whatever path you set) with ?_format=json appended to see your data.

The Views REST Export is remarkably flexible, allowing you to create sophisticated API endpoints for lists of data without writing a single line of code. This is a massive advantage for any Drupal company looking for efficiency.

Authentication and Security: Protecting Your API

Exposing your API means exposing your data, so security is paramount. Without proper authentication and authorization, your data could be vulnerable.

Basic Authentication

For simple, internal applications or when integrating with trusted systems, Basic Auth (basic_auth module in core) can be used. Clients send their Drupal username and password with each request.

Pros: Easy to set up.
Cons: Not very secure as credentials are sent with every request and can be intercepted if not over HTTPS. Not suitable for public-facing APIs or third-party integrations.

Cookie Authentication

When accessing the API from the same domain (e.g., a JavaScript application on the same Drupal site), cookie authentication (cookie module in core) can be used. The user logs into Drupal normally, and subsequent API requests leverage the session cookie.

Pros: Seamless for same-domain applications.
Cons: Not suitable for cross-domain applications or mobile apps.

OAuth 2.0 (Recommended for Third-Party Integrations)

For robust, secure integrations with third-party applications, mobile apps, or decoupled frontends, OAuth 2.0 is the industry standard. Drupal doesn't have OAuth 2.0 in core, but the contributed Simple OAuth module (or oauth2_server) provides excellent functionality.

How it works: Instead of sharing user credentials, OAuth 2.0 allows clients to obtain an "access token" after a user grants permission. This token is then used for subsequent API requests and can be revoked.
Pros: Highly secure, scalable, widely adopted.
Cons: More complex to set up.

If you hire a Drupal developer for a decoupled project, they will almost certainly implement OAuth 2.0 for API security.

JWT (JSON Web Tokens)

JWT is another popular method, often used in conjunction with OAuth 2.0 or as a standalone authentication mechanism for stateless APIs. The contributed JWT module can facilitate this.

Pros: Stateless, compact, self-contained.
Cons: Can be more complex to implement securely, token revocation requires careful handling.

Best Practices for API Security:

Always use HTTPS: Encrypt all API communication to prevent eavesdropping. This is non-negotiable for any Drupal company.
Implement Rate Limiting: Prevent abuse and denial-of-service attacks by limiting the number of requests a client can make in a given timeframe. The contributed Rate Limit module can help.
Validate Input: Thoroughly validate all data sent to your API to prevent injection attacks and ensure data integrity.
Sanitize Output: Ensure data sent from your API is properly sanitized to prevent XSS vulnerabilities in consuming applications.
Principle of Least Privilege: Grant only the necessary permissions to API clients and users.
API Key Management: For simple public APIs, consider API keys, but understand their limitations.
Regular Security Audits: Have your API endpoints and overall Drupal security regularly audited.

Documenting Your API: Crucial for Developers

An API is only as good as its documentation. Without clear, comprehensive documentation, other developers (or even future you) will struggle to understand and use your API.

Swagger/OpenAPI: The industry standard for documenting REST APIs. The contributed OpenAPI / Swagger UI module integrates perfectly with Drupal, automatically generating documentation from your REST resources.
Clear Examples: Provide examples of request and response payloads.
Endpoint Descriptions: Explain what each endpoint does, its parameters, and expected responses.
Authentication Details: Clearly outline how to authenticate with your API.

For a Drupal development agency, providing excellent API documentation is a mark of professionalism and greatly enhances the developer experience.

Common Use Cases for Drupal APIs

The applications for a Drupal API are vast:

Content Hub: A single Drupal instance serving content to multiple websites, mobile apps, and digital signage.
E-commerce Integration: Connecting Drupal Commerce data (products, orders, customers) with external inventory systems or payment gateways.
CRM Integration: Synchronizing user data or lead generation forms with Salesforce, HubSpot, or other CRM systems.
Marketing Automation: Feeding content into email marketing platforms or social media scheduling tools.
Personalized User Experiences: Delivering tailored content based on user profiles or behavior to different frontends.

A proficient Drupal company will explore these use cases to maximize the value of their Drupal investment.

Monitoring and Maintenance: Keeping Your API Healthy

Once your API is live, it's not a "set it and forget it" situation. Ongoing monitoring and maintenance are crucial:

Error Logging: Monitor your Drupal logs for any API-related errors.
Performance Monitoring: Track API response times and throughput. Slow APIs lead to poor user experiences. Tools like New Relic or Datadog can be invaluable.
Version Control: As your API evolves, implement versioning (e.g., /api/v1/articles, /api/v2/articles) to avoid breaking existing client applications.
Security Updates: Keep your Drupal core and contributed modules (especially API-related ones) up-to-date to patch any security vulnerabilities. This is a fundamental responsibility of any Drupal developer.

Conclusion: Unlocking Drupal's Full Potential with APIs

Exposing your API in Drupal might seem like a daunting task at first, but with Drupal's robust core features and powerful contributed modules, it's an achievable goal for beginners and an essential skill for experienced developers. By following the steps outlined in this guide, you can transform your Drupal website development efforts from static websites into dynamic data hubs, ready to power a new generation of interconnected applications.

Whether you're looking to hire a Drupal developer to build a complex decoupled application or you're a Drupal development agency aiming to provide cutting-edge solutions, mastering API exposure is key to unlocking Drupal's full potential.

Ready to take your Drupal site to the next level? Start experimenting with exposing your data today, and witness the power of a truly connected web.

Call to Action: Have you successfully exposed your Drupal API? Share your experiences and tips in the comments below! If you're looking for expert assistance with Drupal website development and API integration, contact a reputable Drupal company for a consultation.