Werkzeug started as a simple collection of various utilities for WSGI applications and has become one of the most advanced WSGI utility modules. It includes a powerful debugger, full featured request and response objects, HTTP utilities to handle entity tags, cache control headers, HTTP dates, cookie handling, file uploads, a powerful URL routing system, and a bunch of community contributed addon modules. Werkzeug is Unicode aware and doesn't enforce a specific template engine, database adapter, or anything else.
