WhoDat Portable is no longer functional due to ARIN changing the responses from their WHOIS server causing lookups to fail. So, WhoDat needs some fixing to work properly. The app is written in C++ using QT. The original base app has been abandoned by the developer but we have the source available on the WhoDat Portable homepage linked above. It's licensed under the GPL so we can continue developing it.
I managed to get it working over here. I won't have the time to maintain the app's future bugs unfortunately.
Link to bug explanation -> https://github.com/PortableApps/WhoDat/issues/1