REST APIs (Representational State Transfer) are a crucial part of modern web development. They enable applications to communicate over the internet in a standardized way. However, a common misconception is that REST APIs are just about using HTTP methods like GET, POST, PUT, and DELETE.
One of the core principles of a truly RESTful API is that it must be hypertext-driven. This means that clients should be able to navigate the API dynamically through links, rather than relying on hardcoded URLs. This concept is known as HATEOAS (Hypermedia as the Engine of Application State).
In this topic, we’ll explore why REST APIs must be hypertext-driven, how HATEOAS works, and why it is essential for building scalable, flexible, and truly RESTful services.
What Does “Hypertext-Driven” Mean in REST APIs?
A hypertext-driven REST API follows the principle that all interactions should be guided by hypermedia links included in the API responses. Instead of clients having to know every possible API endpoint in advance, they receive a response that contains links guiding them to the next available actions.
This approach is similar to how humans navigate the web-by clicking on links rather than manually typing URLs. In RESTful APIs, the client should be able to discover the API’s capabilities dynamically, without prior knowledge of its structure.
What Is HATEOAS?
Definition of HATEOAS
HATEOAS (Hypermedia as the Engine of Application State) is a constraint of REST that dictates that clients interact with the API entirely through hyperlinks provided in responses.
In simpler terms, instead of expecting clients to hardcode API endpoints, the server provides relevant links in the responses to guide the client on what to do next.
Why REST APIs Must Be Hypertext-Driven
Many APIs claim to be RESTful, but they fail to implement HATEOAS properly. True REST APIs must be hypertext-driven for several reasons:
1. Decouples Clients from Server Implementation
If an API is not hypertext-driven, clients must hardcode URLs, making them tightly coupled to the server’s structure. If the API changes, clients may break.
By using HATEOAS, clients rely only on links provided by the server, making the system more flexible and easier to maintain.
2. Enables Dynamic API Exploration
A hypertext-driven API allows clients to explore available options dynamically. Clients do not need documentation for every endpoint-they can simply follow links provided in responses.
This makes APIs more self-descriptive and reduces the dependency on external documentation.
3. Improves API Evolvability
When new features are added to the API, clients don’t need to be updated as long as they follow the provided links. This makes the API more future-proof and adaptable to changes.
4. Enhances Discoverability and Usability
Clients don’t need to know all the endpoints in advance. Just like browsing a website, they can follow links to find the next available actions.
For example, if a client receives a user profile response, it might contain links to update the profile, delete the account, or fetch user orders.
Example of a Hypertext-Driven REST API
Non-Hypertext-Driven API (Bad Example)
{'id': 123,'name': 'John Doe','email': '[email protected]'}In this example, the client has no information about what actions it can take next. It must already know the API structure.
Hypertext-Driven API with HATEOAS (Good Example)
{'id': 123,'name': 'John Doe','email': '[email protected]','links': {'self': '/users/123','edit': '/users/123/edit','delete': '/users/123/delete','orders': '/users/123/orders'}}In this case, the client can dynamically discover actions without hardcoding endpoints. If the API structure changes, the client only needs to follow the links provided.
Implementing Hypertext-Driven REST APIs
1. Use Standard Hypermedia Formats
Several formats can be used to implement hypermedia-driven APIs, such as:
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HAL (Hypertext Application Language)
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JSON-LD (JSON for Linked Data)
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Sirene
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Collection+JSON
For example, a HAL-based API response would look like this:
{'_links': {'self': { 'href': '/users/123' },'edit': { 'href': '/users/123/edit' },'delete': { 'href': '/users/123/delete' },'orders': { 'href': '/users/123/orders' }}}2. Follow RESTful API Best Practices
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Use resource-oriented URLs (e.g.,
/users/123/ordersinstead of/getOrdersByUserId). -
Use proper HTTP methods (
GET,POST,PUT,DELETE). -
Ensure responses are self-descriptive and include hypermedia links.
3. Provide Meaningful Links in Responses
When designing an API, always think about what actions a client might need next and include relevant links in responses.
For example, an API response for an order should include links to:
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View order details
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Cancel the order
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Track the shipment
{'order_id': 987,'status': 'Shipped','tracking_number': 'ABC123','links': {'self': '/orders/987','cancel': '/orders/987/cancel','track': '/orders/987/track'}}This ensures that clients can navigate the API efficiently without needing hardcoded URLs.
Common Challenges in Implementing Hypertext-Driven APIs
1. Increased Complexity
Building hypertext-driven APIs requires more thought and planning, as you must include relevant links in every response.
2. Requires Client-Side Support
Not all API clients are designed to handle hypermedia. You may need to educate developers on how to properly use HATEOAS.
3. Performance Considerations
Including links in every response can increase payload size, potentially impacting performance. Proper optimization is necessary to balance usability and efficiency.
A true REST API must be hypertext-driven by following the HATEOAS principle. This ensures that clients can dynamically explore and interact with the API without prior knowledge of its structure.
By implementing hypermedia-driven APIs, you achieve:
✅ Decoupled clients and servers
✅ Easier API evolution
✅ Better discoverability
✅ More flexible and scalable systems
While implementing HATEOAS requires additional effort, the long-term benefits make it a best practice for building truly RESTful APIs. If you want your API to be future-proof and easier to maintain, embracing hypermedia is the way to go.