appengine-rest-server is a drop-in server for Google App Engine applications that exposes your data model via a REST API with no extra work.
AROUNDMe Personal identity server is a Web site builder with an OpenID server and consumer, allowing you to manage your own OpenID Internet identity.
astahttpd web server
astahttpd is a Web server written in pure PHP. It supports basic HTTP methods such as GET, POST, and HEAD. It also support Alias directories and has CGI processing capabilities. The main aim of astahttpd is to be easy to install and configure, especially for PHP programmers.
CAMAS is a GPL-ed (free for commercial and personal use) web server written in Pike and in C. It is originally based on the Roxen Challenger 1.3 code base.
DAViCal is a server implementation of the CalDAV protocol for storing calendaring resources (iCalendar format) on a remote shared server.
Nanoweb is an HTTP server written in PHP, designed to be small, secure, and extensible. Features include: HTTP/1.1 compliance, FastCGI, CGI and Server side includes support, Name and port based virtual hosts, htpasswd, MySQL, PostgreSQL and LDAP authentication support, and a modular architecture.
OpenResty is a full-fledged web application server by bundling the standard nginx core, lots of 3rd-party nginx modules, as well as most of their external dependencies.
PHP OpenID Standalone Server
PHP OpenID Standalone Server functions as a standalone OpenID server and supports Yadis service discovery, the Simple Registration Extension, and admin-controlled or public account creation. MySQL and the JanRain PHP OpenID library are required.
SAP R/3 Communications Suite
The project purpose is to allow SAP R/3 servers to communicate with external devices such as fax and GSM modems by sending and receiving a fax or SMS. The system provides an easy way of configuration based on web interface and JMX console.
Ultima Linux is a Slackware-based system that aims to be fast, powerful, stable, and secure, for Intel-compatible computers.
uWSGI is a fast, self-healing, developer-friendly WSGI server, meant for professional deployment and development of Python Web applications.
WAWAS is a full PHP application server. The main server core listens to any IP/port and passes data to any mounted protocol on the listener.
WSO2 Web Services Application Server
WSO2 WSAS is an integrated Web services platform which offers a complete middleware solution. It is a lightweight, high performing platform for Service Oriented Architectures, enabling business logic and applications. Bringing together a number of Apache Web services projects, WSO2 WSAS provides a secure, transactional, and reliable runtime for deploying and managing Web services. It features data services support, Eclipse IDE integration, clustering support, full support for WS-Security, WS-Trust, WS-Policy, and WS-Secure Conversation and XKMS, and EJB service provider support.
µWS is one of the most lightweight, efficient & scalable WebSocket server implementations available. It features an easy-to-use, fully async object-oriented interface and scales to millions of connections using only a fraction of memory compared to the competition.