tree: 77f2166d0df50d6e13cfd008d02266bdfcc0e17d [path history] [tgz]
  1. compatibility_tests/
  2. keys/
  3. protos/
  4. src/
  5. .gitignore
  6. build_packages.bat
  9. CHANGES.txt
  11. global.json
  12. Google.Protobuf.Tools.nuspec
  13. Google.Protobuf.Tools.targets

This directory contains the C# Protocol Buffers runtime library.


The easiest way how to use C# protobufs is via the Google.Protobuf NuGet package. Just add the NuGet package to your VS project.

You will also want to install the Google.Protobuf.Tools NuGet package, which contains precompiled version of protoc.exe and a copy of well known .proto files under the package's tools directory.

To generate C# files from your .proto files, invoke protoc with the --csharp_out option.

Supported platforms

The runtime library is built as a portable class library, supporting:

  • .NET 4.5
  • Windows 8
  • Windows Phone Silverlight 8
  • Windows Phone 8.1
  • .NET Core

You should be able to use Protocol Buffers in Visual Studio 2012 and all later versions. This includes all code generated by protoc, which only uses features from C# 3 and earlier.


Open the src/Google.Protobuf.sln solution in Visual Studio 2017 or later.

Although users of this project are only expected to have Visual Studio 2012 or later, developers of the library are required to have Visual Studio 2017 or later, as the library uses C# 6 features in its implementation, as well as the new Visual Studio 2017 csproj format. These features have no impact when using the compiled code - they're only relevant when building the Google.Protobuf assembly.

In order to run and debug the AddressBook example in the IDE, you must install the optional component, “.Net Core 1.0 - 1.1 development tools for Web” (as it's labelled in current versions of the VS2017 installer), above and beyond the main .NET Core cross-platform development feature.


The unit tests use NUnit 3. Tests can be run using the Visual Studio Test Explorer or dotnet test.

.NET 3.5

We don‘t officially support .NET 3.5. However, there has been some effort to make enabling .NET 3.5 support relatively painless in case you require it. There’s no guarantee that this will continue in the future, so rely on .NET 3.5 support at your peril.

To enable .NET 3.5 support, you must edit the TargetFrameworks elements of src/Google.Protobuf/Google.Protobuf.csproj (and src/Google.Protobuf.Test/Google.Protobuf.Test.csproj if you want to run the unit tests):

Open the .csproj file in a text editor and simply add net35 to the list of target frameworks, noting that the TargetFrameworks element appears twice in the file (once in the first PropertyGroup element, and again in the second PropertyGroup element, i.e., the one with the conditional).

History of C# protobufs

This subtree was originally imported from and represents the latest development version of C# protobufs, that will now be developed and maintained by Google. All the development will be done in open, under this repository (

The previous project differs from this project in a number of ways:

  • The old code only supported proto2; the new code only supports proto3 (so no unknown fields, no required/optional distinction, no extensions)
  • The old code was based on immutable message types and builders for them
  • The old code did not support maps or oneof
  • The old code had its own JSON representation, whereas the new code uses the standard protobuf JSON representation
  • The old code had no notion of the “well-known types” which have special support in the new code
  • The old project supported some older platforms (such as older versions of Silverlight) which are not currently supported in the new project