The importance of HTTP status codes to REST-based APIs

HTTP status codes are essential for REST-based APIs, as they provide a standard way of communication between the server and the client and handle errors.

a year ago   •   4 min read

By Kelvin Omereshone
Table of contents

HTTP status codes play a crucial role in REST-based APIs.

These codes, which are three-digit numbers returned by a server in response to an HTTP request, indicate the status of the requested operation and provide important information about how the client should proceed.

Let's take a look at some ways HTTP status codes are important to REST-based APIs in this article.

Consistent communication standards

When designing or exposing a REST-based APIs, it's important to keep in mind HTTP status codes as they serve as a universal way to communicate the status of the response a server sends back to a client after a request is made.

One of the key benefits of using HTTP status codes in REST-based APIs is that they provide a standard way for the server to communicate the outcome of a request to the client.

By using status codes like 200 (OK) and 404 (Not Found), API providers can ensure that their API clients understand the results of their requests, even if the client and server are written in different programming languages or run on different platforms.

One benefit of the REST-based architecture for APIs is that the clients and servers don't need to be in the same language and one of the mechanisms that let both client and server to understand one another even if they are not written in the same programming language is the HTTP status codes as it transcends languages being a numeric representation of the outcome of a request.

Clarity in requests outcomes

With HTTP status codes, one does not need to look at the body of the response sent back from the server before knowing whether the request was successful, or something went wrong.

This comes really handy for clients as they can be sure that when a request returns a status code of 200 for example, the expected result was sent back from the client(hopefully) and can proceed to handling the business logic that a successful response requires.

Because of this clarity, it's very expedient that API providers follow the standard HTTP status codes, and not only should they not create their own status codes for their REST-based APIs, but they should also use the appropriate ones that are provided by HTTP as much as possible.

For more on using the appropriate HTTP status code, take for example, in the HTTP specification, when a creation of a new resource is made on the server via a request, like signing up a new user, a status code of 201 should be returned and not 200.

Both 201 and 200 may seem close enough that one can send 200 in place of 201 as the status code but think about a scenario where clients are checking for the exact status code to do stuff.

If you send an approximation of a status code (a 201 is expected but you sent a 200), you might mislead the client, or the clients will furthermore need to check for ranges in the status codes in order to do a form of catch all to handle the response.

In all, with the appropriate status codes, clients can almost always have clarity on the requests outcome and can make implementations around that.

Troubleshooting made easy

With HTTP status code, one can easily troubleshoot API requests. For example, on my Treblle dashboard, I can filter for requests by status codes.

Since HTTP status codes are consistent, one can trouble shoot for status codes that are not 200 and what that translates to, is finding requests that has a problem (except for 300 status codes which are redirects).

Also, client consuming the API can quickly identify the source of a problem and take next steps on that. For example, when a client encounters one of the 400 status codes, they can infer that the problem is client side and let their client-side error handling kick in.

Uniform error handling

Another important aspect of HTTP status codes is that they allow API consumers to handle errors and exceptions in a uniform way.

For example, if a client attempts to access a resource that doesn't exist, the server can return a 404 status code, which indicates that the requested resource could not be found.

This allows the client to handle the error gracefully and take appropriate action, such as redirecting the user to a different page or displaying an error message.

In other words, the client doesn't have to implement separate error handling for all the APIs it may be consuming and just "trust" to check the HTTP status codes and handle errors using what status codes was sent back from the server with the response.

API security

HTTP status codes also play a key role in API security. By returning a 401 (Unauthorized) or 403 (Forbidden) status code, the server can indicate that the client does not have permission to access a particular resource. This can help prevent unauthorized access to sensitive data and protect against potential security threats.

Indicate progress

HTTP status codes can be used to indicate the progress of a long-running operation, such as a file upload.

For example, a server might return a 202 (Accepted) status code to indicate that the request has been received and is being processed, and a 200 (OK) status code when the operation is complete.


In conclusion, HTTP status codes play a crucial role in REST-based APIs. They provide a standard way for the server to communicate the outcome of a request to the client and handle errors in a consistent manner. They also enhance the security of the API by indicating when a client does not have permission to access a particular resource.

Without the use of HTTP status codes, it would be difficult for API providers to ensure that their API clients understand the results of their requests, handle exceptions and ensure the security of their resources.

Therefore, it is important to use HTTP status codes in the development of REST-based APIs to ensure they are robust and reliable.

HTTP status codes also provide additional information to developers and operations teams when debugging and monitoring APIs.

Speaking about debugging and monitoring APIs, Treblle makes it easy to both debug and monitor your REST-based APIs. Sign up today

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