Fiddler for Mac

Wireshark is the world's foremost network protocol analyzer, and is the de facto (and often de jure) standard across many industries and educational institutions.

Charles is an HTTP proxy that enables a developer to view all of the HTTP and SSL or HTTPS traffic between their machine and the Internet. This includes requests, responses and the HTTP headers (which contain the cookies and caching information).

WebScarab is a framework for analysing applications that communicate using the HTTP and HTTPS protocols. It is written in Java, and is thus portable to many platforms. WebScarab has several modes of operation, implemented by a number of plugins.

HTTP Client is a developer tool for debugging HTTP services by graphically creating and inspecting complex HTTP messages. Features: - HTTP methods: GET, POST, PUT, DELETE, TRACE, OPTIONS, HEAD, CONNECT

The Zed Attack Proxy (ZAP) is an easy to use integrated penetration testing tool for finding vulnerabilities in web applications.

Burp Suite is an integrated platform for performing security testing of web applications. Its various tools work seamlessly together to support the entire testing process, from initial mapping and analysis of an application's attack...

HTTP Scoop passively listens for HTTP requests from any browser (or other application for that matter) running on your Mac. If you're running a web server or an application server on your machine then you will see requests going to that too.

Graphical Http Client is a lightweight and easy to use Mac OS X utility that will help you test and interact with REST-based web services.

Andiparos is a security tool that can be used for web application security assessments. Main features: - Smartcard support. - BeanShell support. - History Filter (URLs). - Passive Scanner. - Advanced search functionality.

HTTPTester allows you to send HTTP requests with full control over headers, post parameters, and cookies. You can edit cookies sent by websites or add some of your own.