How to choose a free audio-to-MIDI converter

There are a lot of free "audio to MIDI" tools online, and most of their landing pages read the same: upload a file, get MIDI, no install. The differences that actually matter are underneath that pitch. Here's what to actually check.

What model is doing the transcription?

Most free web-based converters aren't training their own transcription model — they're wrapping one of a small number of open-source or research models. Spotify's Basic Pitch (the model behind MelodyTrace) is one of the most common, because it's free, lightweight, and instrument-agnostic. If a tool won't tell you what model it uses, that's worth noticing — it usually means you can't look up its published accuracy either. We wrote up what Basic Pitch's own ICASSP 2022 paper reports by instrument: strong on guitar, weaker on piano relative to specialized tools, decent on vocals. Any tool built on the same model will have roughly the same strengths and the same limits, regardless of what its marketing copy claims.

Can you fix a wrong note, or is it one-shot?

No transcription model gets every note right — see the benchmarks above. The real product question is what happens next. Some tools give you a MIDI file and nothing else: if three notes are wrong, you're opening a DAW to fix them by hand, or living with them. Others — including MelodyTrace — put the result on an interactive piano roll first, so you can delete a stray note, adjust detection sensitivity, and re-transcribe before you ever download anything. For anything more complex than a simple monophonic line, this step is the difference between a usable transcription and a rough draft you have to redo elsewhere.

Does it export sheet music, or only MIDI?

If you want notation — for teaching, practicing, or arranging — check whether a tool stops at a .mid file or can also export MusicXML/PDF. Going from audio to notation is a two-step process (audio → MIDI → engraved score, not a direct model), so a tool that only does step one leaves you finding a separate notation tool for step two. See Audio to Sheet Music if this is what you need.

What are the real free-tier limits?

"Free" tools vary a lot on file size and duration caps, how many conversions you get before hitting a paywall or signup wall, and whether preview/editing is free even if export isn't. Check these before you commit ten minutes uploading a file, not after.

What happens to your file?

A tool that processes your audio has to do something with it, even briefly. Read the privacy policy for retention (is it deleted after processing, and when?) before uploading anything you wouldn't want stored somewhere. MelodyTrace's own practices are in our Privacy Policy.

Is it actually free, or "free" until you need the feature you came for?

Watch for tools where "free" covers only the demo — real export, batch processing, or higher-quality models are paywalled. That's a legitimate business model, but check whether the specific thing you need (a full MIDI download, not a truncated preview) is actually included before you invest time.

Where MelodyTrace fits

MelodyTrace is Basic Pitch under the hood (same model discussed above, published accuracy and all — we don't claim otherwise), with free browser-based conversion and preview, no account needed for the core MP3/WAV-to-MIDI flow, an editable piano roll to fix notes before you commit to a result, and MusicXML/PDF sheet-music export alongside MIDI. It's a reasonable default if those specific things matter to you; it isn't the right tool if you need multi-track stem separation or a desktop app that works offline — nothing web-based does either of those well yet.

Related

• How accurate is audio-to-MIDI transcription? — the underlying model's published numbers by instrument.
• MP3 to MIDI · Audio to Sheet Music · MIDI to Sheet Music