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Working with Headers in Postman

? Working with Headers in Postman

? Quick Overview

HTTP headers are key-value pairs sent along with requests and responses. In Postman, headers such as Content-Type, Authorization, and Custom Headers help define how data is sent, secured, and interpreted by servers.

? Key Concepts

  • Content-Type – Defines the media type of the request body
  • Authorization – Carries credentials or tokens
  • Custom Headers – Application-specific metadata
  • Headers are case-insensitive
  • Multiple headers can be sent in a single request

? Syntax / Theory

In HTTP, headers follow a simple format:

Header-Name: Header-Value

Postman automatically manages some headers, but you can add or override them manually in the Headers tab.

? Code Example(s)

? View Code Example 
// Example of common HTTP headers used in Postman
Content-Type: application/json
Authorization: Bearer YOUR_ACCESS_TOKEN
X-Custom-Client: PostmanDemo

? Live Output / Explanation

What Happens?

  • Content-Type tells the server to expect JSON data
  • Authorization sends a Bearer token for secured APIs
  • X-Custom-Client is a user-defined header for tracking or logic

?️ Interactive Example

Use the inputs below to simulate adding headers to a request.

GET /api/v1/users HTTP/1.1
Host: api.example.com
// Headers you add will appear here...
? View Code Example 
// Simulating header attachment in JavaScript
const headers = {
"Content-Type": "application/json",
"Authorization": "Bearer demo_token",
"X-App-Version": "1.0.0"
};
console.log(headers);

? Use Cases

  • Sending JSON or XML data to REST APIs
  • Authenticating requests using tokens or API keys
  • Passing versioning or client information
  • Feature toggles and A/B testing via headers

? Tips & Best Practices

  • Let Postman auto-generate headers when possible
  • Avoid sending sensitive data in custom headers unnecessarily
  • Use environment variables for tokens
  • Keep header names meaningful and consistent

? Try It Yourself

  1. Create a new request in Postman
  2. Add Content-Type: application/json
  3. Add a dummy Authorization token
  4. Send the request to a public API like https://httpbin.org/headers
  5. Observe the headers echoed back in the response