Yeah there's a few websites like that, like https://songcraft.io/ , https://autochords.com/ , https://chordbot.com/ as well as online DAWs like https://www.bandlab.com/ , https://www.audiotool.com/. Source: almost 3 years ago

Yeah, sure. I use Lossless Audio Checker, which is single threaded but seems to generate fewer false negatives. That is to say it's slow, but doesn't flag genuine lossless files as probable mpegs as much. My biggest beef with LAC is how annoying it is about its log files. It doesn't save them in the folder with the FLACs so I have to manually copy every log file from my Documents folder to the proper location.... Source: about 1 year ago

You can use this to check for artificially inflated bitrate/bitdepth, its fairly accurate, or fbits which can detect exactly how much of the bitdepth is being used. Source: almost 2 years ago

If you have Windows, the Lossless Audio Checker can tell you in about 2 seconds if a WAV or FLAC file has been upsampled/ upscaled/ transcoded. There is also a CLI version for Mac. Source: over 2 years ago

Losslessaudiochecker.com paired with spek.cc when in doubt gets the job done. Source: over 2 years ago

I read about it about a year ago and recently did some tests using https://losslessaudiochecker.com/ to see for myself. And indeed, some songs 320 or FLAC audio files I sourced from deezer were upscaled. Source: over 2 years ago