ua_parser C# Library

April 15, 2026 · View on GitHub

This is the CSharp implementation of ua-parser. You can find the latest binaries on NuGet here.

Build status

The implementation uses the shared regex patterns and overrides from regexes.yaml (found in uap-core). The assembly embeds the latest regex patterns (enabled through a git submodule) which are loaded into the default parser. You can create a parser with more updated regex patterns by using the static methods on Parser to pass in specific patterns in yaml format.

Build and Run Tests:

Make sure you pull down the submodules that includes the yaml files (otherwise you won't be able to compile):

git submodule update --init --recursive

You can then build and run the tests by invoking the build.bat script

.\build.bat

Update the embedded regexes

To pull the latest regexes into the project:

cd uap-core
git pull origin master

Usage:

  using UAParser;

...

  string uaString = "Mozilla/5.0 (iPhone; CPU iPhone OS 5_1_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9B206 Safari/7534.48.3";

  // Create the parser once and reuse it. Parser construction parses the embedded
  // yaml and builds regex structures, so avoid creating a parser per request.
  var uaParser = Parser.GetDefault();

  // get a parser using externally supplied yaml definitions
  // var uaParser = Parser.FromYaml(yamlString);

  ClientInfo c = uaParser.Parse(uaString);

  Console.WriteLine(c.UA.Family); // => "Mobile Safari"
  Console.WriteLine(c.UA.Major);  // => "5"
  Console.WriteLine(c.UA.Minor);  // => "1"

  Console.WriteLine(c.OS.Family);        // => "iOS"
  Console.WriteLine(c.OS.Major);         // => "5"
  Console.WriteLine(c.OS.Minor);         // => "1"

  Console.WriteLine(c.Device.Family);    // => "iPhone"

In ASP.NET Core, register the parser as a singleton and inject it where needed:

using UAParser;

builder.Services.AddSingleton(_ => Parser.GetDefault());

If you construct a parser with Parser.FromYaml(...) or Parser.GetDefault(new ParserOptions { ... }), cache and reuse that instance as well instead of creating it on each request.

Authors: