AmazingMIDI is described as 'Free WAV to MIDI converter for music transcription. AmazingMIDI automatically transcribes music, converting WAV files into MIDI files. It can recognize single-instrument polyphonic music'. There are five alternatives to AmazingMIDI for Mac, Windows, Linux, Online / Web-based and Self-Hosted solutions. The best alternative is AnthemScore. It's not free, so if you're looking for a free alternative, you could try Piano Scribe. Other great apps like AmazingMIDI are WIDI Recognition System (Paid), Neuratron AudioScore (Paid) and MuDic (Paid).
Piano Scribe converts raw audio to MIDI using Onsets and Frames, a neural network trained for polyphonic piano transcription. Record yourself playing piano or choose an audio file with solo piano from your device to transcribe!
WIDI Recognition System is a complete solution for automated and computer assisted music transcription. WIDI takes musical audio in mp3, wave, CD-Track or other formats as input and produces scores as output. The result scores can be saved as MIDI sequences.