User Agent Parser for Python

1.0.1 · active · verified Sun Mar 29

ua-parser is a Python port of Browserscope's user agent parser. It provides functionality to detect details like browser, operating system, CPU, and device type/model from a given User-Agent string. The library is actively maintained, with its latest version being 1.0.1, and releases are made to keep up with user agent string changes, although core regex updates can sometimes require specific attention.

Warnings

gotcha Without installing optional dependencies like 'regex' or 'google-re2', the library relies on a pure Python resolver which is significantly slower, especially on non-CPython runtimes. This can lead to unexpected performance bottlenecks.
Fix: Install with recommended optional dependencies: `pip install 'ua-parser[regex]'` for optimal performance.
breaking Google Chrome is progressively 'freezing' User-Agent strings and moving towards User-Agent Client Hints. Libraries relying solely on traditional User-Agent strings (like `ua-parser` by default) may experience declining accuracy for modern Chrome browsers over time as less information is available in the frozen string.
Fix: Be aware of this industry shift. Consider supplementing `ua-parser` with a solution that handles User-Agent Client Hints if high accuracy for Chrome is critical. The `ua-parser` library itself does not inherently parse client hints.
gotcha The accuracy of user agent parsing relies on up-to-date regex definitions. While `ua-parser` is maintained, keeping its internal regexes current with the latest devices and browsers might require manual updates or more frequent dependency updates compared to solutions that offer automatic regex updates.
Fix: Regularly update the `ua-parser` library to benefit from the latest regex definitions. For critical applications, monitor parsing results and consider how the underlying `uap-core` definitions are updated.
deprecated In versions prior to 1.0 (e.g., 0.x), the parser could be re-created on every access if not explicitly handled, negating the benefits of faster regex engines and caching. This was a common performance footgun.
Fix: Upgrade to `ua-parser` version 1.0 or newer. If staying on 0.x, ensure the global parser is explicitly set or cached to avoid re-creation overhead.

Install

pip install ua-parser Basic Installation
pip install 'ua-parser[regex]' Recommended (Faster Regex Engine)
pip install 'ua-parser[re2]' Alternative (Google RE2 Engine)
pip install 'ua-parser[yaml]' With YAML Ruleset Loading

Imports

parse
```
from ua_parser import parse
```
parse_user_agent
```
from ua_parser import parse_user_agent
```
parse_os
```
from ua_parser import parse_os
```
parse_device
```
from ua_parser import parse_device
```

Quickstart

This quickstart demonstrates how to use `ua-parser` to parse common User-Agent strings and extract information about the browser, operating system, and device. The `parse` function returns a Result object containing detailed attributes.

from ua_parser import parse

# Example User-Agent strings
ua_string_desktop = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36'
ua_string_mobile = 'Mozilla/5.0 (iPhone; CPU iPhone OS 17_4_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.4.1 Mobile/15E148 Safari/604.1'

# Parse a desktop User-Agent string
parsed_ua_desktop = parse(ua_string_desktop)
print(f"Desktop UA: {ua_string_desktop}")
print(f"  Browser: {parsed_ua_desktop.user_agent.family} {parsed_ua_desktop.user_agent.major}.{parsed_ua_desktop.user_agent.minor}")
print(f"  OS: {parsed_ua_desktop.os.family} {parsed_ua_desktop.os.major}.{parsed_ua_desktop.os.minor}")
print(f"  Device: {parsed_ua_desktop.device.family}\n")

# Parse a mobile User-Agent string
parsed_ua_mobile = parse(ua_string_mobile)
print(f"Mobile UA: {ua_string_mobile}")
print(f"  Browser: {parsed_ua_mobile.user_agent.family} {parsed_ua_mobile.user_agent.major}.{parsed_ua_mobile.user_agent.minor}")
print(f"  OS: {parsed_ua_mobile.os.family} {parsed_ua_mobile.os.major}.{parsed_ua_mobile.os.minor}")
print(f"  Device: {parsed_ua_mobile.device.family}")

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