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Fast, cross-platform HTTP/2 web server with automatic HTTPS
Turn any program that uses STDIN/STDOUT into a WebSocket server. Like inetd, but for WebSockets.
Fluentd: Unified Logging Layer (project under CNCF)
HTTP Request & Response Service, written in Python + Flask.
Small, fast, modern HTTP server for Erlang/OTP.
gunicorn 'Green Unicorn' is a WSGI HTTP Server for UNIX, fast clients and sleepy applications.
POCO C++ Libraries - Cross-platform C++ libraries with a network/internet focus.
A Microservice Toolkit from The New York Times
http-kit is a minimalist, event-driven, high-performance Clojure HTTP server/client library with WebSocket and asynchronous support
Eclipse Jetty® - Web Container & Clients - supports HTTP/2, HTTP/1.1, HTTP/1.0, websocket, servlets, and more
A simple and visual static web server with collaboration features.
Webmachine, the HTTP toolkit (in Ruby)