DeleGate is a multi-purpose application level gateway or proxy server that mediates communication of various protocols, applying cache and conversion for mediated data, controlling access from clients, and routing toward servers. It translates protocols between clients and servers, converting between IPv4 and IPv6, applying SSL (TLS) to arbitrary protocols, merging several servers into a single server view with aliasing and filtering. It can be used as a simple origin server for some protocols (HTTP, FTP, and NNTP).
FilterProxy is a Perl script that acts as a generic Web proxy. It is unique in that it allows you to install modules that can perform arbitrary transformations on HTML (or any other MIME-type) and HTTP headers. It filters ads by stripping HTML from the page, anonymizes requests by removing Referer and User-Agent headers, compresses HTML content, and de-animates animated gifs. Configuration is done via Web-based forms or editing a Perl data structure.
HTTPGate is a filtering HTTP Gateway originally intended to enchange user's privacy when surfing on the net, but it can also be used to avoid censorware systems in web browsing. HTTPGate operates on a user definable internet port where the user connects using a web browser. The main page shows a text box and a set of options user can choose to avoid transmitting some information during client/server negotiation.
httpMonitor is a Python program which lets you monitor the HTTP traffic between a browser and a Web server. You configure your browser to use httpMonitor as its proxy to ensure that all HTTP traffic between browser and server goes via httpMonitor. In a XML-configuration file you can specify a Python-function as processor for the HTTP-messages you are interested in (requests or responses, which match certain criteria). You may have as many processors as you want, without modifying the actual program. The only thing you need to do is configure the httpMonitor and write your processors.
RabbIt is a mutating, caching Web proxy used to speed up surfing over slow links like modems. It does this by removing advertising and background images and scaling down images to low quality JPEGs. RabbIT is written in Java and should be able to run on any platform. It does depend upon an image converter if image scaling is on. The recommended image converter is "convert" from the ImageMagick package.
rproxy is an extension to HTTP which allows transferring of differences between a web server and client, using an algorithm similar to rsync's. This works particularly well for dynamically-generated sites, where the pages are often similar but not the same on each visit. Transferring just the difference reduces network traffic and therefore loading time.
squid_redirect uses a list of patterns to zap annoying ad banners from Web pages, inserting a placeholder image. It lives in a Web proxy and so requires no special browser facilities. It's readily customizable, small, fast, and easy to install. (In Debian/Ubuntu, this program is named "adzapper".)
Tinyproxy is a light-weight HTTP/HTTPS proxy daemon for POSIX operating systems. Designed from the ground up to be fast and yet small, it is an ideal solution for use cases such as embedded deployments where a full featured HTTP proxy is required, but the system resources for a larger proxy are unavailable.