HTTP Archive : The HTTP Archive tracks how the Web is built.
httpbin.org : A simple HTTP Request & Response Service.
Hurl : Hurl is a command line tool that runs HTTP requests defined in a simple plain text format.
It can chain requests, capture values and evaluate queries ...
CouchDB : Apache CouchDB™ is a database
that uses JSON for documents,
JavaScript for MapReduce indexes,
and regular HTTP for its API