WebBrowserExtensionsLoadUrlWithPostData Method

Creates a new instance of IRequest with the specified Url and Method = POST and then calls LoadRequest(IRequest). LoadRequest(IRequest) can only be used if a renderer process already exists. In newer versions initially loading about:blank no longer creates a renderer process. You can load a Data Uri initially then call this method. https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs

public static void LoadUrlWithPostData(
	this IWebBrowser browser,
	string url,
	byte[] postDataBytes,
	string contentType = null
)

public:
[ExtensionAttribute]
static void LoadUrlWithPostData(
	IWebBrowser^ browser, 
	String^ url, 
	array<unsigned char>^ postDataBytes, 
	String^ contentType = nullptr
)