---
title: Custom HTTP Headers
description: "HTTP headers allow you to customize requests to match real-world scenarios. They're essential for testing APIs, authenticated endpoints, and browser-like behavior. ## User-Agent ****Identifies the client making the request. Servers may respond differently based on this header.**** ****Example:**** SiteLoadTester/1.0 or…"
url: "https://ssh-assistant.com/docs/custom-http-headers/"
updated: "2025-12-06"
category: Site Load Tester / Load tester
---

# Custom HTTP Headers

HTTP headers allow you to customize requests to match real-world scenarios. They're essential for testing APIs, authenticated endpoints, and browser-like behavior.

## User-Agent

****Identifies the client making the request. Servers may respond differently based on this header.****

****Example:**** SiteLoadTester/1.0 or Mozilla/5.0...

****Use Cases:****

- Test mobile vs desktop responses

- Bypass bot detection

- Simulate specific browser behavior

## Accept

****Specifies which content types the client can handle. Affects what format the server returns.****

****Example:**** text/html,application/json or application/json

****Use Cases:****

- Test API endpoints (use application/json)

- Ensure correct content type responses

- Test content negotiation

## Authorization

****Contains credentials for authenticated requests. Required for protected endpoints.****

****Example:**** Bearer YOUR_TOKEN or Basic base64(username:password)

****Use Cases:****

- Test authenticated API endpoints

- Load test protected resources

- Verify token-based authentication performance

**### Content-Type**

****Indicates the media type of the request body. Required for POST/PUT requests with data.****

****Example:**** application/json or application/x-www-form-urlencoded

****Use Cases:****

- Test API endpoints that accept JSON

- Simulate form submissions

- Test file upload endpoints

## Referer

****Shows the URL of the page that linked to the current request. Used for analytics and security.****

****Example:**** https://example.com/page

****Use Cases:****

- Test referral-based logic

- Simulate navigation flows

- Test analytics tracking

## Origin

****Indicates the origin of the request. Used for CORS (Cross-Origin Resource Sharing) checks.****

****Example:**** https://example.com

****Use Cases:****

- Test CORS policies

- Simulate cross-origin requests

- Test API security configurations

## X-Requested-With

****Indicates the request was made via XMLHttpRequest. Often used to distinguish AJAX from regular requests.****

****Example:**** XMLHttpRequest

****Use Cases:****

- Test AJAX endpoint performance

- Simulate single-page app behavior

- Test API endpoints expecting AJAX

## Accept-Language

****Specifies which languages the client prefers. Affects internationalization and localization.****

****Example:**** en-US,en;q=0.9 or es-ES,es;q=0.9

****Use Cases:****

- Test multi-language sites

- Verify localization performance

- Test language-based routing

## Why Custom Headers Matter

- ****Realistic Testing:**** Headers make your load tests behave like real browsers or API clients, giving you accurate performance metrics.

- ****Security Testing:**** Test how your server handles authenticated requests, CORS policies, and security headers under load.

- ****Behavior Simulation:**** Simulate different client types (mobile, desktop, API clients) to see how your server responds to each.

- ****Performance Analysis:**** Compare performance differences between content types, authentication methods, and client configurations.

## Important Notes

- Only test servers you own or have explicit permission to test

- High connection counts (500+) may be blocked by firewalls or rate limiters

- Monitor your own network bandwidth when running heavy tests

- Some servers may temporarily block your IP if tests are too aggressive