Post vs. Put: Understanding the Key Differences

In the world of web development and API design, two HTTP methods often come under scrutiny for their roles in creating and updating resources – POST and PUT. Understanding the differences between these two methods is crucial for developers as they navigate the principles of RESTful architecture and ensure that their APIs function as intended. Both methods are used for sending data to the server, but their usage scenarios and effects on the server and resources are distinct.

The Main Difference between Post and Put

Post vs. Put: Key Takeaways

  • POST creates new resources, while PUT updates existing ones or creates them at a specific URL.
  • Use POST when the server is responsible for generating the resource’s new URI.
  • Choose PUT when the client dictates the exact location and nature of the resource.

Post vs. Put: Understanding the Key Differences in HTTP Methods

Post vs. Put: Understanding HTTP Methods

Definition of POST

POST is an HTTP method used to send data to a server for creating or updating a resource. When we use POST, we’re typically submitting a form, uploading a file, or performing actions that result in a change of state or the creation of a new resource.

Definition of PUT

PUT, in contrast, is an HTTP method that is used for updating existing resources or creating a new resource at a specific URI. When we use PUT, we’re making sure that the server updates an existing resource with a complete new version provided by the client or creates one at the specified URI if it does not already exist.

Post vs. Put: Usage

When to Use POST over PUT

Creating New Resources: We use POST when we want to create a new resource on the server and the client does not dictate the resource’s URI. In fact, the server typically assigns a unique URI for the new resource after it’s created.

  • POST is the correct choice when the operation might result in different outcomes on successive calls.
  • If the action involves sending data to the server to create a sub-resource under a collection of resources, we go with POST.

Non-idempotent Operations: We opt for POST when the operation has side effects and is non-idempotent. This means if you repeat the request multiple times, you’ll likely get different results each time.

  • For operations where user input is processed and a response is generated without storing the input permanently, POST is our method.

Sending Large Payloads: When the request size exceeds certain limits, or when the input is of a variable size, POST is a better choice.

  • PUT requests are idempotent and the URI should be known beforehand, which often makes them unsuitable for large or dynamic data operations.
Criteria POST Usage
New Resource Creation When the client can’t assign the URI
Non-Idempotent Operations When successive calls can produce different outcomes
Unpredictable Request Size Suitable for sending large or variable-sized payloads

When to Use PUT over POST

PUT is Idempotent: We choose PUT when we want our operation to be idempotent. This means that multiple identical requests should yield the same result. If we’re updating a resource at a specific URL and we send the same PUT request multiple times, it should have no further effect after its initial application.

Updating Resources: If we’re updating an entire resource or replacing it at a known URL, PUT is the way to go. For example, if we have a user profile identified by a unique ID, we’d use PUT to update their entire profile.

When Not to Create Resources: We use PUT when we don’t intend to create new resources on repeated submissions. In contrast, POST may generate a new resource each time it’s called.

Method Use Case
POST Create new resources, non-idempotent calls
PUT Update/replace resources at a known URL

Here’s a simple checklist to determine if PUT suits our situation:

  • Do we have the URL of the resource? PUT is designed for resource-specific endpoints.
  • Are we updating a resource in full? PUT accepts the complete representation of a resource.
  • Is idempotence important? For safety and predictability in repeated requests, we use PUT.

Post vs. Put: Key Differences

Resource Identification No unique URI needed Specific URI required
Idempotency Non-idempotent Idempotent
Operation Use Create new resources Update existing or Create at specified URI
  • IdempotencyPOST actions can produce different results even if the same request is repeated, making it non-idempotent. PUT should return the same result, making it idempotent.

Post vs. Put: Example Sentences

Post Examples

  • The web form uses an HTTP post request to submit user data to the server.
  • To create a new user account, the application sends a post request with the user’s details.
  • The API documentation specifies that a post method should be used for adding new items to the database.
  • When you click the ‘Submit’ button, it triggers a post request that sends your information to the server.
  • The developer wrote a script that makes a post call to the server every time a file is uploaded.
  • To handle the post request, the server-side script processes the incoming data and responds accordingly.
  • The error message indicated that the post request failed because the server did not receive the expected data.

Put Examples

  • The RESTful API requires you to use a put request when updating the user’s profile information.
  • If the record does not exist, the server might allow the put request to create a new resource with the given URI.
  • To change the settings, you need to send a put request with the updated configuration JSON.
  • The put method is idempotent, meaning that multiple identical put requests should have the same effect as a single request.
  • When syncing files, the client software issues a put request to update the contents on the server.
  • The developer used a put request in the application to overwrite an existing resource with new data.
  • For partial updates, it’s often recommended to use PATCH instead of put, as put typically replaces the entire resource.

Related Confused Words with Post or Put

Put vs. Patch

In the context of HTTP methods, PUT and PATCH are used to update resources on a server, but they differ in how they handle the update:


  • PUT is used to update an entire resource or create a new one if it doesn’t exist at the specified URL.
  • When you use PUT, you provide a complete, updated version of the resource. This means that any fields not included in the request will typically be erased or reverted to default values.
  • PUT is idempotent, meaning that making multiple identical requests will have the same effect as making a single request.


  • PATCH is used for partial updates to a resource, meaning you only need to send the data that you want to change.
  • Unlike PUT, PATCH requests only modify the specified fields of the resource, leaving the rest of it unchanged.
  • PATCH is also generally considered idempotent, although it can be implemented in non-idempotent ways depending on how the server processes the partial update.

Post vs. Get


  • The GET method requests data from a specified resource. It is used to retrieve information from the server.
  • Data sent by GET method is appended to the URL as a query string and is visible in the browser’s address bar, which has length limitations.
  • GET requests can be cached, bookmarked, and remain in the browser history.
  • They should not be used for sensitive data, as the information is exposed in the URL.
  • GET is considered idempotent, meaning that it can be repeated without causing different results or side effects.


  • The POST method submits data to be processed to a specified resource. It is often used when submitting form data or uploading a file.
  • Data sent by POST method goes through the request body, which has no size limitations, making it more secure for sensitive data.
  • POST requests are not cached, cannot be bookmarked, and do not remain in the browser history.
  • They are used to create or update a resource on the server.
  • POST is not idempotent, which means submitting the same POST request multiple times may result in different outcomes, such as creating multiple entries.