Rat proxy

Ratproxy is a semi-automated, largely passive web application security audit tool. It is meant to complement active crawlers and manual proxies more commonly used for this task, and is optimized specifically for an accurate and sensitive detection, and automatic annotation, of potential problems and security-relevant design patterns based on the observation of existing, user-initiated traffic in complex web 2.0 environments.

ssl strip proxy

sslstrip is an SSL stripping proxy, designed to make unencrypted HTTP sessions look as much as possible like HTTPS sessions. It converts https links to http or to https with a known private key. It even provides a padlock favicon for the illusion of a secure channel. Many HTTPS sites are normally accessed from a redirect on an HTTP page, and many users don't notice when their connection isn't upgraded.

Fiddler proxy

Fiddler is a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP(S) traffic, set breakpoints, and "fiddle" with incoming or outgoing data. Fiddler includes a powerful event-based scripting subsystem, and can be extended using any .NET language.

Paros proxy

A Java-based web proxy for assessing web application vulnerability. It supports editing/viewing HTTP/HTTPS messages on-the-fly to change items such as cookies and form fields. It includes a web traffic recorder, web spider, hash calculator, and a scanner for testing common web application attacks such as SQL injection and cross-site scripting.