Best JSON and Base64 libraries for C++ and Windows

The application in previous post Is my system a hybrid (switchable) graphics system? is implemented in C++/WinRT, which I finally decided to give a try.

For authoring and consuming Windows Runtime APIs using C++, there is C++/WinRT. This is Microsoft’s recommended replacement for the C++/CX language projection, and the Windows Runtime C++ Template Library (WRL).

The real question here is this: is WRL at all adopted yet? However it is already superseded by a new thing!

What is really cool about C++/WinRT though – and I do like the most of it – is that good old fashioned apps like desktop and even console ones can seamlessly consume UWP APIs. And this is the field where new and revised API appear now in first place.

If you, for instance, have a need in JSON lib for C++ code, Windows.Data.Json API is at your service. You no longer need a lib for this and many other routine tasks. Here is how you would parse and stringify JSON in plain C++:

std::wstring EncodeBase64(const BYTE* Data, SIZE_T DataSize)
	winrt::Windows::Storage::Streams::Buffer Buffer(static_cast<UINT32>(DataSize));
	std::memcpy(, Data, DataSize);
	const winrt::hstring Text = winrt::Windows::Security::Cryptography::CryptographicBuffer::EncodeToBase64String(Buffer);
	return static_cast<std::wstring>(Text);
std::wstring EncodeBase64(const std::string& Value)
	return EncodeBase64(reinterpret_cast<const BYTE*>(, Value.size());
std::wstring EncodeBase64(const std::wstring& Value)
	return EncodeBase64(ToMultiByte(Value, CP_UTF8));
std::wstring EncodeBase64(const winrt::Windows::Data::Json::JsonObject& Value)
	return EncodeBase64(static_cast<std::wstring>(Value.Stringify()));

std::wstring DecodeBase64(const std::wstring& Value)
	winrt::Windows::Storage::Streams::IBuffer Buffer { winrt::Windows::Security::Cryptography::CryptographicBuffer::DecodeFromBase64String(Value) };
	const UINT32 Length = Buffer.Length();
	std::string Result(Length, 0);
	std::memcpy(,, Length);
	return FromMultiByte(Result);
winrt::Windows::Data::Json::JsonObject DecodeBase64AsJsonObject(const std::wstring& Value)
	return { winrt::Windows::Data::Json::JsonObject::Parse(DecodeBase64(Value)) };

This thing can cope with XAML too, and if you get the hump just go read on on C++/WinRT use of co_await and friends for built-in support for UWP IAsyncAction.

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