Devd is a console-based open source HTTP server, aimed at developers but also simple enough for anyone to use.
How simple? It's just one executable, no other components required, and you don't have to mess around with lengthy and complex configuration files.
Instead, the developer suggests this as a quick start:
devd -ol .
This command opens a browser window to display the current folder (or you can just type 127.0.0.1 in another browser whenever you like), and reloads your site when files change.
Browse your site and devd displays a colour-coded log of what's happening in your console window.
This is great for quick testing, but there's also reverse proxy support (devd -w ./src http://localhost:8080), throttling and latency simulation, smart routing and a few other extras for more experienced users to try.