The general consensus in python-ideas is that the following is needed, so I bring it to python-dev to final discussions before I file a feature request in bugs.python.org. Proposal: add add_query_params() for appending query parameters to an URL to urllib.parse and urlparse. Implementation: http://github.com/mrts/qparams/blob/83d1ec287ec10934b5e637455819cf796b1b421c... free to fork and comment). Behaviour (longish, guided by "simple things are simiple, complex things possible"): In the simplest form, parameters can be passed via keyword arguments: >>> add_query_params('foo', bar='baz') 'foo?bar=baz' >>> add_query_params('http://example.com/a/b/c?a=b', b='d') 'http://example.com/a/b/c?a=b&b=d' Note that '/', if given in arguments, is encoded: >>> add_query_params('http://example.com/a/b/c?a=b', b='d', foo='/bar') 'http://example.com/a/b/c?a=b&b=d&foo=%2Fbar' Duplicates are discarded: >>> add_query_params('http://example.com/a/b/c?a=b', a='b') 'http://example.com/a/b/c?a=b' >>> add_query_params('http://example.com/a/b/c?a=b&c=q', a='b', b='d', ... c='q') 'http://example.com/a/b/c?a=b&c=q&b=d' But different values for the same key are supported: >>> add_query_params('http://example.com/a/b/c?a=b', a='c', b='d') 'http://example.com/a/b/c?a=b&a=c&b=d' Pass different values for a single key in a list (again, duplicates are removed): >>> add_query_params('http://example.com/a/b/c?a=b', a=('q', 'b', 'c'), ... b='d') 'http://example.com/a/b/c?a=b&a=q&a=c&b=d' Keys with no value are respected, pass ``None`` to create one: >>> add_query_params('http://example.com/a/b/c?a', b=None) 'http://example.com/a/b/c?a&b' But if a value is given, the empty key is considered a duplicate (i.e. the case of a&a=b is considered nonsensical): >>> add_query_params('http://example.com/a/b/c?a', a='b', c=None) 'http://example.com/a/b/c?a=b&c' If you need to pass in key names that are not allowed in keyword arguments, pass them via a dictionary in second argument: >>> add_query_params('foo', {"+'|äüö": 'bar'}) 'foo?%2B%27%7C%C3%A4%C3%BC%C3%B6=bar' Order of original parameters is retained, although similar keys are grouped together. Order of keyword arguments is not (and can not be) retained: >>> add_query_params('foo?a=b&b=c&a=b&a=d', a='b') 'foo?a=b&a=d&b=c' >>> add_query_params('http://example.com/a/b/c?a=b&q=c&e=d', ... x='y', e=1, o=2) 'http://example.com/a/b/c?a=b&q=c&e=d&e=1&x=y&o=2' If you need to retain the order of the added parameters, use an :class:`OrderedDict` as the second argument (*params_dict*): >>> from collections import OrderedDict >>> od = OrderedDict() >>> od['xavier'] = 1 >>> od['abacus'] = 2 >>> od['janus'] = 3 >>> add_query_params('http://example.com/a/b/c?a=b', od) 'http://example.com/a/b/c?a=b&xavier=1&abacus=2&janus=3' If both *params_dict* and keyword arguments are provided, values from the former are used before the latter: >>> add_query_params('http://example.com/a/b/c?a=b', od, xavier=1.1, ... zorg='a', alpha='b', watt='c', borg='d') ' http://example.com/a/b/c?a=b&xavier=1&xavier=1.1&abacus=2&janus=3&zorg=a&borg=d&watt=c&alpha=b ' Do nothing with a single argument: >>> add_query_params('a') 'a' >>> add_query_params('arbitrary strange stuff?öäüõ*()+-=42') 'arbitrary strange stuff?\xc3\xb6\xc3\xa4\xc3\xbc\xc3\xb5*()+-=42'