python - Parsing HTTP User-Agent string

51
votes

What is the best method to parse a User-Agent string in Python to reliably detect

  1. Browser
  2. Browser version
  3. OS

Or perhaps any helper library that does it

8
pythonhttphttp-headersuser-agent
More to the point, depending on browser OSes and versions for capability detection is not a good strategy. What problem are you trying to solve? - Dan Davies Brackett
We have a simple ticket reporter form for our web app. And we frequently ask users what's the broswer/OS etc. So we might just detect it beforehand and ask the user to confirm. Well, if thats not so trivial we will just dump the user-agent but still need to ask questions, as user might be using a different browser to submit the ticket. - Shekhar
You may wish to just let Python render the form and use Javascript to change the input field values to those of the current OS and what ever else you wish. - NerdyNick

8 Answers

74
votes

I finally decided to write my own, and I am happy with the outcome. Please feel free to use/modify/send me patches, etc.

It's here: http://pypi.python.org/pypi/httpagentparser

Usage example:

>>> import httpagentparser
>>> s = "Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/532.9 (KHTML, like Gecko) \
        Chrome/5.0.307.11 Safari/532.9"
>>> print(httpagentparser.simple_detect(s))
('Linux', 'Chrome 5.0.307.11')
>>> print(httpagentparser.detect(s))
{'os': {'name': 'Linux'},
 'browser': {'version': '5.0.307.11', 'name': 'Chrome'}}

>>> s = "Mozilla/5.0 (Linux; U; Android 2.3.5; en-in; HTC_DesireS_S510e Build/GRJ90) \
        AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1"
>>> print(httpagentparser.simple_detect(s))
('Android Linux 2.3.5', 'Safari 4.0')
>>> print(httpagentparser.detect(s))
{'dist': {'version': '2.3.5', 'name': 'Android'},
'os': {'name': 'Linux'},
'browser': {'version': '4.0', 'name': 'Safari'}}
10
votes

UASparser for Python by Hicro Kee. Auto updated datafile and cache from remote server with version checking.

8
votes

Werkzeug has user-agent parsing built-in.

New link (Jun 2018) http://werkzeug.pocoo.org/docs/0.14/utils/#module-werkzeug.useragents

7
votes

The other responses to this question are rather old now. I believe the new standard in Browser User Agent parsing is Browserscope's user agent parser.

Also conveniently available with the exact same matching patterns in many other languages. Someday you might want to also parse some UA strings in JavaScript and you don't need to worry about inconsistent parsing.

6
votes

Having run these suggestions against the full corpus of Firefox User Agents, I've found that the version-number parsing for comparison is quite poor.

If that's what you need, I suggest that you take a look at UAparser, which used to be part of the browserscope project. Documentation here.

3
votes

Th Browser Cap Parser should work. It may be a bit slow though..

2
votes

However if you wish to parse all this on the Python side you can use the XML/INI files provided at http://browsers.garykeith.com/downloads.asp to do lookups on the user agent. This is the same file that is used in php's get_browser() function.

1
votes

As this is not about an open source solution, I doubt this will become the first answer. Anyway, when it comes to User-Agent analysis, the de-facto standard is WURFL (now a commercial product.

Here is a reference to the technical docs.

https://docs.scientiamobile.com/documentation/infuze/infuze-python-module-user-guide

In addition to that, WURFL Microservice is available on the major Cloud Providers marketplaces and also supports a Python client: