How do I use python for web development without relying on a framework?

The way to go is wsgi.

WSGI is the Web Server Gateway Interface. It is a specification for web servers and application servers to communicate with web applications (though it can also be used for more than that). It is a Python standard, described in detail in PEP 333.

All current frameworks support wsgi. A lot of webservers support it also (apache included, through mod_wsgi). It is the way to go if you want to write your own framework.

Here is hello world, written to wsgi directly:

def application(environ, start_response):    status = '200 OK'    response_headers = [('Content-type','text/plain')]    start_response(status, response_headers)    return ['Hello world!\n']

Put this in a file.py, point your mod_wsgi apache configuration to it, and it will run. Pure python. No imports. Just a python function.

If you are really writing your own framework, you could check werkzeug. It is not a framework, but 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. Takes the boring part out of your hands.

It's hilarious how, even prompted with a question asking how to write without a framework, everyone still piles in to promote their favourite framework. The OP whinges about not wanting a “heavyweight framework”, and the replies mention Twisted, of all things?! Come now, really.

Yes, it is perfectly possible to write straight WSGI apps, and grab bits of wanted functionality from standalone modules, instead of fitting your code into one particular framework's view of the world.

To take this route you'll generally want to be familiar with the basics of HTTP and CGI (since WSGI inherits an awful lot from that earlier specification). It's not necessarily an approach to recommend to beginners, but it's quite doable.

I'd like to hear about all the conspicuous, minimal yet powerful approaches

You won't hear about them, because no-one has a tribal interest in promoting “do it yourself” as a methodology. Me, I use a particular standalone templating package, a particular standalone form-reading package, a particular data access layer, and a few home-brew utility modules. I'm not writing to one particular philosophy I can proselytise about, they're all just boring tools that could be swapped out and replaced with something else just as good.

You could also check cherrypy. The focus of cherrypy is in being a framework that lets you write python. Cherrypy has its own pretty good webserver, but it is wsgi-compatible so you can run cherrypy applications in apache via mod_wsgi. Here is hello world in cherrypy:

import cherrypyclass HelloWorld(object):    def index(self):        return "Hello World!"    index.exposed = Truecherrypy.quickstart(HelloWorld())