What do you need Fiddler for?

Fiddler is used by me for the following purposes:

• Intercepting and analyzing HTTP/HTTPS traffic: Allows tracking requests and responses between the client and server.
• Debugging web applications: Helps identify issues with requests, responses, headers, cookies, and message bodies.
• Emulating various conditions: Using FiddlerScript, requests and responses can be modified "on the fly," simulating different scenarios (e.g., slow connection, server errors).
• API testing: Convenient for sending custom requests and analyzing responses from APIs.
• Performance testing: Allows evaluating resource load times and identifying "bottlenecks".
• Using AutoResponder: For mocking responses or redirecting requests.

Example of using FiddlerScript to change the User-Agent header:

// Example of changing the User-Agent header
if (oSession.HostnameIs("example.com"))
{
    oSession.RequestHeaders["User-Agent"] = "MyCustomUserAgent/1.0";
}

Example table with traffic types that can be analyzed:

Traffic Type	Description
HTTP	Unencrypted traffic between client and server
HTTPS	Encrypted traffic (requires certificate installation)
WebSocket	Bidirectional real-time connection