We have used a C++ Requests package.
Note- Use https:// in the url.
#include <cpr/cpr.h>
int main(int argc, char** argv) {
auto r = cpr::Get(cpr::Url{"https://unfurl.io/api/v2/preview?api_token=yourapitoken&url=https://www.google.com"});
r.status_code; // 200
r.header["content-type"]; // application/json; charset=utf-8
r.text; // JSON text string
}