BrotliSharpLib 0.3.3

.NET Standard 1.1 .NET Framework 2.0
dotnet add package BrotliSharpLib --version 0.3.3
NuGet\Install-Package BrotliSharpLib -Version 0.3.3
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="BrotliSharpLib" Version="0.3.3" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add BrotliSharpLib --version 0.3.3
#r "nuget: BrotliSharpLib, 0.3.3"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install BrotliSharpLib as a Cake Addin
#addin nuget:?package=BrotliSharpLib&version=0.3.3

// Install BrotliSharpLib as a Cake Tool
#tool nuget:?package=BrotliSharpLib&version=0.3.3


BrotliSharpLib is a full C# port of the brotli library/compression code by Google. It is intended to be a mostly 1:1 conversion of the original C code. All code is correct as of v0.6.0 of the reference implementation.

The projects uses a minimal set of APIs to ensure compatibility with a wide range of frameworks including .NET Standard and .NET Core. It also supports little-endian and big-endian architectures and is optimised for x86, x64 and ARM processors.

BrotliSharpLib is licensed under MIT.


BrotliSharpLib can be installed via the NuGet package here.

Install-Package BrotliSharpLib


Generic/basic usage:

/** Decompression **/
byte[] brotliCompressedData = ...; // arbritary data source
byte[] uncompressedData = Brotli.DecompressBuffer(brotliCompressedData, 0, brotliCompressedData.Length /**, customDictionary **/);

/** Compression **/
byte[] uncompressedData = ...; // arbritary data source

// By default, brotli uses a quality value of 11 and window size of 22 if the parameters are omitted.
byte[] compressedData = Brotli.CompressBuffer(uncompressedData, 0, uncompressedData.Length /**, quality, windowSize, customDictionary **/);

Stream usage:

/** Decompression **/
using (var ms = new MemoryStream())
using (var bs = new BrotliStream(compressedStream, CompressionMode.Decompress))

/** Compression **/
using (var fs = File.OpenRead(filePath))
using (var ms = new MemoryStream())
    using (var bs = new BrotliStream(ms, CompressionMode.Compress))
        // By default, BrotliSharpLib uses a quality value of 1 and window size of 22 if the methods are not called.
        /** bs.SetQuality(quality); **/
        /** bs.SetWindow(windowSize); **/
        /** bs.SetCustomDictionary(customDict); **/
        /* IMPORTANT: Only use the destination stream after closing/disposing the BrotliStream
           as the BrotliStream must be closed in order to signal that no more blocks are being written
           for the final block to be flushed out 
        byte[] compressed = ms.ToArray();

Real-life example: The following allows for acceptance and decompression of brotli encoded web content via a HttpClient and falls back to gzip or deflate when required.

static class HttpClientEx
    private class BrotliCompressionHandler : DelegatingHandler
        protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
            request.Headers.AcceptEncoding.Add(new StringWithQualityHeaderValue("br"));
            var response = await base.SendAsync(request, cancellationToken);
            IEnumerable<string> ce;
            if (response.Content.Headers.TryGetValues("Content-Encoding", out ce) && ce.First() == "br")
                var buffer = await response.Content.ReadAsByteArrayAsync();
                response.Content = new ByteArrayContent(Brotli.DecompressBuffer(buffer, 0, buffer.Length));
            return response;

    public static HttpClient Create()
        var handler = new HttpClientHandler();
        if (handler.SupportsAutomaticDecompression)
            handler.AutomaticDecompression = System.Net.DecompressionMethods.Deflate | System.Net.DecompressionMethods.GZip;
        return HttpClientFactory.Create(handler, new BrotliCompressionHandler());


Considerations for Build

For optimal performance, ensure to build BrotliSharpLib in Release mode to enable all possible JIT optimisations.

Performance can also be further improved by building BrotliSharpLib using .NET Framework 4.5 or above (or any framework that supports AggressiveInlining). Selecting a specific target platform (instead of AnyCPU) where possible can also further improve performance. All of this however, is completely optional as BrotliSharpLib is designed to run in a wide range of contexts and configurations regardless.


The following are benchmark results using DotNetBenchmark with BrotliSharpLib (v0.2.1) and Google's C# implementation built against .NET Framework 4.6.1. The original C version was compiled in Release mode using Visual Studio 2017 (v141) as a 64-bit Windows executable.

BenchmarkDotNet=v0.10.6, OS=Windows 10 Redstone 2 (10.0.15063)
Processor=Intel Core i5-6600K CPU 3.50GHz (Skylake), ProcessorCount=4
Frequency=3421875 Hz, Resolution=292.2374 ns, Timer=TSC
  [Host]       : Clr 4.0.30319.42000, 64bit RyuJIT-v4.7.2046.0
  RyuJitX64    : Clr 4.0.30319.42000, 64bit RyuJIT-v4.7.2046.0

File: UPX v3.91 (Windows Executable)

Method Mean
GoogleImpl 12.75 ms
BrotliSharpLib 11.63 ms
Original C 11.17 ms

As seen above, BrotliSharpLib performs close to the original C version in terms of decompression.


File: plrabn12.txt

Method Quality Mean
BrotliSharpLib 1 9.132 ms
Original C 1 9.570 ms
BrotliSharpLib 6 58.720 ms
Original C 6 36.540 ms
BrotliSharpLib 9 116.318 ms
Original C 9 73.080 ms
BrotliSharpLib 11 1822.702 ms
Original C 11 877.58 ms

While BrotliSharpLib performs comparatively at lower quality levels, it performs up to three times worse at level 11. Future versions of the port will hopefully bring this down.

Product Versions
.NET net5.0 net5.0-windows net6.0 net6.0-android net6.0-ios net6.0-maccatalyst net6.0-macos net6.0-tvos net6.0-windows net7.0 net7.0-android net7.0-ios net7.0-maccatalyst net7.0-macos net7.0-tvos net7.0-windows
.NET Core netcoreapp1.0 netcoreapp1.1 netcoreapp2.0 netcoreapp2.1 netcoreapp2.2 netcoreapp3.0 netcoreapp3.1
.NET Standard netstandard1.1 netstandard1.2 netstandard1.3 netstandard1.4 netstandard1.5 netstandard1.6 netstandard2.0 netstandard2.1
.NET Framework net20 net35 net40 net403 net45 net451 net452 net46 net461 net462 net463 net47 net471 net472 net48 net481
MonoAndroid monoandroid
MonoMac monomac
MonoTouch monotouch
Tizen tizen30 tizen40 tizen60
Universal Windows Platform uap uap10.0
Windows Phone wpa81
Windows Store netcore netcore45 netcore451
Xamarin.iOS xamarinios
Xamarin.Mac xamarinmac
Xamarin.TVOS xamarintvos
Xamarin.WatchOS xamarinwatchos
Compatible target framework(s)
Additional computed target framework(s)
Learn more about Target Frameworks and .NET Standard.

NuGet packages (19)

Showing the top 5 NuGet packages that depend on BrotliSharpLib:

Package Downloads

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GitHub repositories (9)

Showing the top 5 popular GitHub repositories that depend on BrotliSharpLib:

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Version Downloads Last updated
0.3.3 1,930,522 2/6/2019
0.3.2 15,275 12/9/2018
0.3.1 96,838 10/5/2018
0.3.0 8,092 7/3/2018
0.2.1 57,856 7/16/2017
0.2.0 1,636 6/28/2017