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Which REST constraint essentially prohibits the use of cookies?

The advent of distributed systems and the ever-growing demand for high-performance, scalable, and maintainable web applications gave birth to Representational State Transfer (REST) as a software architectural style. REST is built to support the principles of web technology, including the HTTP protocol. It has various architectural constraints, six of which are essential in the definition.

One of the most discussed and yet misunderstood of the REST constraints is the stateless constraint. In this blog, we will discuss this specific constraint and how it essentially prohibits the use of cookies.

The Stateless Constraint in REST

The principle of statelessness is a critical building block of REST and defines that every client-request should carry with it all the information necessary to complete the request. The server should receive no prior context. The argument is that by introducing statefulness in an application, developers introduce complex caching mechanisms and complicate error recovery. Thus, the statelessness constraint aims to simplify the architecture and allow for the scalability of the web application.

The server must store all necessary data to process the requests in the backend, and the client should not rely on receiving responses or data from previous requests. In simpler terms, each request from a client to a server must contain all the information necessary for the server to understand, process, and respond appropriately.

This constraint has several advantages:

  • It simplifies server design since it does not hold any client-state information,
  • It can easily handle many clients at once with less overhead,
  • It ensures that all requests are independent of each other reducing coupling between requests.

The Use of Cookies in Web Applications

Nowadays, web developers commonly use cookies to store client-side information for various use cases. Cookies are small text files that a server can send to a client’s browser when a client accesses a website. The idea is that a generator website can store some information locally that the browser will send back for requests to the same website without needing to send the same information again. This procedure breaks the stateless constraint of REST.

Cookies can have various attributes that affect their life-cycle, including:

  • Expires – defines when the cookie should expire,
  • Domain – specifies the domain of the web application for which the cookie is valid,
  • Path – limits cookie access to a specific directory,
  • HttpOnly – restricts access of the cookie to HTTP requests only, thereby reducing the risk of cross-site scripting attacks.

How Cookies Violate the Stateless Constraint

Cookies preserve state information between web transactions by storing the information client-side in the browser. For example, they can store user preferences like preferences, login credentials and state tracking information for shopping carts. When sent between the client and server, cookies provide a mechanism through which the server can hold client-related state information across several requests.

By storing information on the client-side, cookies allow web applications to keep track of user behavior, session data, and server-side data. This behavior contradicts the REST statelessness constraint and introduces a coupling between the client and the server.

However, it is important to note that cookies do not entirely go against the principles of REST. They can be useful in applications that need to keep track of client-actions periodically or infer behavior on the server-side. Besides, cookies are a vital tool for analytics, personalization, and tracking.

It’s also worth noting that although the use of cookies contradicts the statelessness constraint, it doesn’t necessarily make it a terrible choice for all use cases.


In conclusion, the statelessness constraint is a critical component of the REST API architecture. It’s essential to keep this constraint in mind when working on a RESTful system. The use of cookies in RESTful APIs breaks this constraint. However, there are still cases where using cookies may be useful. As a RESTful developer, it is essential to evaluate when to use cookies, limiting their use to the cases mentioned earlier.

Quality REST API documentation should emphasize the importance of the stateless constraint and discourage the use of cookies except in specific cases. If your API requires more data storage over HTTP, consider using cache mechanisms within the application itself, or include random values that the client must send back to the server with every specific request as headers.

For more information on REST APIs and other REST constraints, visit


Are cookies allowed in REST API?

In short, cookies can be used in REST API. However, to understand the use of cookies in REST API, one must first understand the principles of REST.

The REST (Representational State Transfer) architectural style is an approach to developing web services that emphasizes statelessness and the use of HTTP protocols to exchange data between client and server. RESTful web services use HTTP requests to POST (create), PUT (update), GET (retrieve), and DELETE (delete) data.

One defining characteristic of RESTful web services is their statelessness. That means that all the necessary information to complete a request is contained in that single request. The server does not store any session information related to the client, which allows for greater scalability, modifiability, and reliability.

However, when it comes to authentication, some information has to stay on the server side for security reasons. This is where cookies come in. Cookies are small pieces of data stored by web browsers that are used to keep track of user activity. They are commonly used for authentication purposes, where a server sets a cookie when a user logs in, and that cookie is sent back with subsequent requests to verify the user’s identity.

RESTful web services allow for the use of cookies, but only for authentication purposes. Any session-related data should still be stored on the client side. The server may use a cookie to identify the user making a request, but the client must include the necessary data in the request to complete the action.

Cookies are allowed in REST API for authentication purposes. REST requires that any session information be stored on the client side, but when it comes to authentication, some information has to stay on the server side for security reasons, and cookies are an appropriate means of doing this. However, excessive use of cookies can have negative impacts on the scalability and performance of a web service, so they should be used sparingly and only when necessary.

What are the constraints of REST system?

REST, or Representational State Transfer, is a popular architectural style used for designing web services. REST was first described by Roy Fielding in his PhD thesis, and it has since become the foundation for most web service implementations on the internet.

REST architectural style is based on a set of constraints, which provide a structured framework for designing web services that are scalable, maintainable and flexible. These constraints are:

1. Client-Server constraint
The client-server constraint is the foundation of the REST architecture. It separates the client and server components so that they can evolve independently. It allows for simplicity in components, improved scalability and flexibility.

2. Statelessness constraint
The statelessness constraint means that each request from the client must contain all the information necessary to complete the request. This allows for better performance, scalability and reliability as there is no need for session information to be stored on the server.

3. Cache constraint
The cache constraint allows for the response of a request to be cached on the client side to avoid making multiple identical requests to the server. This lowers network latency, reduces bandwidth usage and improves server performance.

4. Uniform Interface constraint
The uniform interface constraint stipulates that the interaction between the client and the server is standardized. This includes the use of HTTP methods such as GET, PUT, POST, DELETE, etc., and standard formats such as JSON or XML. This constraint allows for better maintainability of the system and allows for multiple clients to be developed independently.

5. Layered System constraint
REST system is designed as a layered architecture of different components. Each layer provides a specific function and only communicates with the layer below it. This constraint improves scalability, reliability and allows for better separation of concerns.

6. Code-On-Demand constraint
The code-on-demand constraint allows for the server to provide executable code to the client on request. This can be beneficial for improving the functionality and flexibility of the system but may pose security risks.

The constraints of the REST architectural style provide a structured framework for designing web services that are flexible, scalable, maintainable and reliable. By adhering to these constraints, RESTful web services can be designed to support different types of clients and provide interoperability between heterogeneous systems.

Which REST constraint allows for the presence of caching?

The new era of web development has brought a lot of advancement in the architectural styles of web applications. Representational State Transfer, or REST, is one of the most widely used architectural styles in modern web development. It is used for designing web applications that can communicate with each other using simple and well-defined principles. REST is built upon a set of constraints that help developers in building web applications that are reliable, scalable, and maintainable.

One of the most important principles of REST is caching. Caching is a mechanism that allows responses from a server to be stored locally at the client-side or at intermediate caches, reducing the number of requests that reach the server in turn improving performance.

The Cache constraint is a very important constraint of the REST architectural style. According to this constraint, the response from a server can be cacheable. With caching, the response can be stored locally at the client-side reducing the number of requests that the client needs to send to the server. This reduces network traffic and saves a significant amount of time, especially when the response is large and complex.

Caching is a powerful mechanism that saves the client from unnecessarily requesting the same data from the server over and over again. Instead, the client can retrieve the response from a local cache, reducing the load on the server and improving the performance of the application.

To summarize, the Cache constraint in REST architectural style allows for the presence of caching, which is a mechanism that reduces the number of requests sent to the server by storing the response locally at the client-side or at intermediate caches. This constraint is a very powerful tool for improving the performance of web applications by reducing the time taken for retrieving data from the server.