Flurl for C# (.NET): Complete Guide with Examples

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Flurl is a modern, elegant library for .NET that combines a fluent URL builder and HTTP client. It is designed to make working with HTTP requests as simple, readable, and convenient as possible. Instead of cumbersome code with HttpClient, UriBuilder, and numerous string concatenations, Flurl offers a concise and expressive syntax reminiscent of method chaining in LINQ.

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Why use Flurl? The main problem with the standard HttpClient is verbosity. To send a simple GET request with parameters and headers, you have to write 10-15 lines of code. Flurl reduces this to 2-3 lines, making the code self-documenting. Additionally, Flurl solves the problem of safe URL construction: it automatically encodes parameters, handles paths and query strings, preventing errors related to incorrect character escaping.

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The library is ideal for any scenario requiring interaction with REST APIs: from simple mobile applications to complex enterprise systems. Flurl supports all major HTTP methods, JSON handling, file uploads, timeouts, retries, and much more. It is fully asynchronous and compatible with .NET Standard 2.0+, allowing its use in .NET Framework, .NET Core, and .NET 5/6/7/8.

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Installation

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Flurl can be installed via NuGet Package Manager. For working with HTTP requests, the Flurl.Http package is required, which also includes Flurl (the URL builder).

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Via .NET CLI:

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dotnet add package Flurl.Http

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Via Package Manager Console:

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Install-Package Flurl.Http

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Via Visual Studio: Right-click on the project → Manage NuGet Packages → search for "Flurl.Http" → Install.

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If you only need the URL builder without the HTTP client, you can install:

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dotnet add package Flurl

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Quick Start

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A minimal working example — fetching data from a public API and printing to the console:

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using Flurl.Http;\nusing System;\nusing System.Threading.Tasks;\n\nclass Program\n{\n    static async Task Main(string[] args)\n    {\n        // GET request to JSON API\n        var response = await "https://jsonplaceholder.typicode.com/posts/1"\n            .GetJsonAsync<dynamic>();\n\n        Console.WriteLine($"Title: {response.title}");\n        Console.WriteLine($"Body: {response.body}");\n    }\n}

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This code makes a GET request, automatically deserializes the JSON response into a dynamic object, and outputs the fields. Note: Flurl allows calling methods directly on a URL string — this is the "fluent" style.

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Main Methods and Classes

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1. Url.Combine() — Safe URL concatenation

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Signature: public static string Combine(params string[] parts)

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What it does: Combines multiple URL parts, automatically adding/removing extra slashes. Prevents duplicate slashes.

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using Flurl;\n\nstring fullUrl = Url.Combine("https://api.example.com", "/v1/", "users", "/123");\nConsole.WriteLine(fullUrl); // https://api.example.com/v1/users/123

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2. Url.SetQueryParams() — Fluent parameter addition

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Signature: public static string SetQueryParams(this string url, object values)

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What it does: Adds query parameters to the URL from an anonymous object or dictionary. Automatically encodes values.

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using Flurl;\n\nstring url = "https://api.example.com/search"\n    .SetQueryParams(new { q = "hello world", page = 1, limit =