PET is a proxy server that works for HTTP (with caching), SSL, and FTP. PET supports extended ICP services (enhanced algorithms) and Cache Digests, both of which are compatible with Squid. It also includes an easy-to-use Web-based configuration interface for nearly all configuration parameters and statistics.
www_proxy is a non-caching HTTP proxy with capability of modifying the User-Agent field. It has customizable content filterig capablity and unlike most proxy servers, it logs the contents of the body of a POST request, not just the header. This tool is handy for debugging CGI scripts, search engine submission programs, bypassing problematic routes and firewalls, and for getting rid of junk HTML content.
LiteSpeed Web Server is a high-performance, secure, easy-to-use, and Apache interchangeable Web server. It supports HTTP/1.1, SSL, CGI, FastCGI, LSAPI, PHP, JSP, Servlets, GZIP compression, chroot, IP level throttling, connection accounting, DoS attack prevention, and instant recovery mechanisms. With its Apache compatible rewrite engine, .htaccess, and MS FrontPage support, migration is quick and easy. A Web interface is included for administration and configuration. It can be used as a content accelerator, compression proxy, or a security guard running in front of any Web and application server.
Obscura is a gallery management system written in PHP and Perl. At approximately 500 lines, it is simple, lightweight, and efficient. By design, it lacks HTTP management and upload; the administrator must have shell access to run the administration script. Output Web pages are formatted using CSS, making modification of fonts and colors easy. The header and footer can also be modified, allowing tight integration with an existing Web site.
EXProxy is a simple HTTP/HTTPS proxy server packaged as a Java library and designed to listen to HTTP requests and responses going through it. It has also the ability to modify requests and responses on the fly. For HTTP over SSL, it uses the "man in the middle" principle, and so will generate warnings about certificates in your Web browser.
BackupMX consists of two programs, 'Store' and 'Forward'. Store accepts SMTP connections, takes all mail given to it, and stores it in a file. Forward takes that file and forwards it over SMTP to a fixed destination. This is code for integrating into your own projects rather than using as is. It is suitable for creating a disaster-recovery mail handler, but would also make a good basis for a spam filter, a tarpit, a honeypot, or a greylist filter. It is written in simple C, and has no external dependencies such as libsmtp.