VirusTotalNet VS VirusTotalUploader

There's quite a few API's out there for this. I can't say what would be best but VirusTotal works OK and there are a number of .Net wrappers for it. Owned by Google/Alphabet but surprisingly hasn't been killed off yet. Unless ownership changed which is always possible with them. As someone else mentioned, Cloudmersive is a thing. Haven't tried it though. I've mostly just gone the ClamAV route in the past.

You shouldn't use Norton, it's not very good. Eset is fine, also, check files with virustotal if you're worried : https://github.com/SamuelTulach/VirusTotalUploader

Defender + weekly Malwarebytes is enough unless you randomly run EXEs from the internet. Upload suspicious file to VirusTotal and unless you're specifically targeted you should be fine.

Nevermind... found it: https://github.com/SamuelTulach/VirusTotalUploader

For future readers, Virustotal had their own (deprecated) uploader shell extension, but these days there's an open-source Virustotal uploader shell extension and OpenHashTab, a file-hashing shell extension, has Virustotal support. If I remember rightly, Process Hacker also has Virustotal support.