What is the difference between POST and PUT in HTTP?

Matthew C.

—February 15, 2023

The Problem

You can send data to a server using an HTTP request that uses the POST or PUT method. When should each HTTP method be used?

The Solution

The HTTP request POST method sends data to a server in a request body. HTML form data is typically sent to the server using a POST request. The server can use this data to add the sent data to a database.

The HTTP PUT method is used to create a new resource or replace a resource. It’s similar to the POST method, in that it sends data to a server, but it’s idempotent. This means that the effect of multiple PUT requests should be the same as one PUT request.

For example, you may have a book review app that has an /add-book API route that you could send book data to. The sent book data can then be added to a database on the server. Making multiple POST requests to this API will create multiple book entries in the database.

Your book review app may also have an /edit-book/id API route that allows you to edit a book by its ID. API requests to this route would be suited to PUT requests that will replace the book information in the database with the data in the request payload. Multiple PUT requests to edit the book data will result in the same data change as one PUT request to edit the data.

Note however that these definitions are only defined by the HTTP specifications for POST and PUT. In reality, it is up to software engineers to implement POST and PUT into applications as recommended by the specification, and a correct implementation is not always guaranteed.