The POST method sends data to a server and creates new records. Testers use POST requests to validate data creation workflows in APIs. Let’s explore its purpose, flow, and testing approach.

What Is the POST Method?

POST helps the client send data to the server. It is used when a new item must be stored or processed. Example use cases:

• Register a user
• Add a new product
• Create a booking
• Upload a profile picture
• Post a comment

POST places the request data inside the body. This makes POST ideal for structured data like JSON or files.

How POST Request Works

The POST request triggers a server action. Here is the simple flow:

• Client prepares data in the request body
• Server validates the data
• Server stores the new record
• Server sends a response confirming success

Example JSON body:

{

"name": "Sam",

"email": "sam@example.com"

}

The server returns: 201 Created. This tells the user that the record exists now.

Key Characteristics of POST

This method focuses on creation and change. Each action may add new data. Characteristics of POST method are:

• Creates new resources
• Sends data in the body
• Supports authentication
• Triggers workflows on the server

Important behavior note: Calling the same POST twice creates duplicates. So POST is not idempotent (unless handled by the logic in the backend). Common response codes in API response are:

• 201 Created — New item stored
• 200 OK — Action completed
• 400 Bad Request — Wrong input
• 401 Unauthorized — Login required
• 500 Internal Server Error — Server failed

Why POST Matters in API Testing

POST requests need strong validation from testers. Issues can cause data loss or security risks.

Top things to verify:

• Required fields work
• Correct data types
• Duplicate handling
• Authentication rules
• DB data stored correctly
• Status codes match behavior
• Proper error messages
• No unwanted access allowed

Testers should also check DB logs. This ensures that POST did not create extra records.

Real-World Example

Consider an e-commerce app:

• You add an item to the cart → POST request
• You confirm your order → POST request

Every important “save” action depends on POST.

A bug here may break the entire workflow.

Summary: When to Use POST

POST sends data and creates something new.

Use POST whenever the server needs new information stored.

Quick rule: If the action adds data → choose POST.