Short answer: none of the three publishes a fully comparable, independently verified accuracy score you can drop into a spreadsheet. Basic Pitch is the only one with a reproducible, peer-reviewed benchmark (its authors report note-level F1 in the low 0.9s on the MUSDB transcription set). OpenMusic publishes a self-reported range — roughly 85–95% on single-line (monophonic) audio and 70–85% on mixed (polyphonic) audio — but discloses no test set, no metric definition, and no independent audit. jukeblocks (built by AudioShake) publishes no accuracy numbers at all. So "which is accurate" is not a brand question; it is an "on your audio, measured how" question. The rest of this guide gives you the metrics that actually matter and a test you can run today.
What "accurate" actually means (the part vendors skip)
A single "accuracy %" hides at least five different failures. If you want to judge a converter honestly, score it on these separately:
| Dimension | What it measures | How it fails in practice |
|---|---|---|
| Note F1 | The balance of notes correctly detected vs. missed or invented | Extra ghost notes, or whole phrases dropped |
| Onset precision | Are note starts placed on the right beat? | Notes drift early/late; grooves feel wrong |
| Pitch accuracy | Are the detected pitches correct? | Octave errors, wrong notes in chords |
| Polyphony handling | Does it keep simultaneous parts separate? | Bass and melody collide into one line |
| Instrument fit | Does it suit the source (drums vs. voice vs. piano)? | Drums come out as pitched mush |
A tool can score 90% on one and 40% on another. That is why a bare "95% accurate" claim — when one exists — tells you almost nothing until you know which dimension it refers to.
What each tool actually discloses about accuracy
| Tool | Publishes a number? | What's behind it | Reproducible? |
|---|---|---|---|
| Basic Pitch (Spotify) | Yes — peer-reviewed | Note F1 ~0.91 on MUSDB, methodology open | Yes, you can re-run it |
| OpenMusic | Yes — self-reported | 85–95% mono / 70–85% poly, no dataset named | No |
| jukeblocks (AudioShake) | No | "Studio-grade" language, no metric | No |
The asymmetry is the real story. Basic Pitch's number comes from a paper you can read and a model you can run on your own files, so its claim is checkable. OpenMusic's number is a marketing range with no disclosed methodology, so it is asserted. jukeblocks makes no measurable claim at all. None of the three has been benchmarked against the same held-out dataset by an independent party, so any head-to-head "X beat Y" statement you see is either a vendor claim or a hobbyist anecdote — not data.
The benchmark reality: only Basic Pitch is checkable
Because Basic Pitch is open source, its accuracy is the only one you can verify end to end. The model was evaluated on MUSDB, a standard music-transcription corpus, and the published note-level F1 sits in the low 0.9s. That does not mean "91% on your song" — MUSDB is clean-ish studio material, and your phone recording of a noisy room will score lower. But the number is real, the dataset is named, and the code is public, which puts it in a different category from the others.
OpenMusic's range, by contrast, is plausible but unverifiable: "monophonic 85–95%" could mean anything from "notes timed to the nearest beat" to "pitch correct within a semitone," and the audio it was tested on is never described. Treat it as a ceiling estimate, not a measurement.
jukeblocks' strength is its parent company's stem-separation lineage (AudioShake), which suggests good separation of mixed sources — but separation quality is not the same as transcription accuracy, and no published figure lets you confirm it.
A DIY accuracy test you can run this afternoon
You do not need a lab. You need one clean reference and the same file pushed through all three. Here is a procedure that produces a number you can trust for your use case.
- Pick one short clip (8–20 seconds). Use something you can notate by ear: a single sung line, a simple piano phrase, or one bass riff. Avoid a full mix for the first pass.
- Build a ground truth. In your DAW or notation app, hand-enter what you hear as MIDI. Keep it to the notes that actually matter. This is your reference.
- Run the clip through each tool. Export MIDI from Basic Pitch (local), jukeblocks (web upload), and OpenMusic (web). Save three files.
- Align and count. Load each output under your ground truth on the same timeline. For each true note, mark: correct pitch + correct timing (hit), correct pitch only (off), or missed/invented (wrong).
- Score it. Use this rubric:
| Score | Rule |
|---|---|
| Note hit | Pitch correct AND onset within ~60 ms of reference |
| Note soft | Pitch correct but timing off by more than 60 ms |
| Note miss | Wrong pitch, or note absent, or ghost note not in reference |
Then Accuracy = hits / (hits + soft + miss). Run it on three different clips (voice, piano, dense mix) and average. You now have a personal, source-specific number for each tool — which is the only accuracy that affects your work.
What to expect by source type
Based on how each system is built (not on marketing), here is a realistic expectation before you even test:
| Source | Basic Pitch | jukeblocks | OpenMusic |
|---|---|---|---|
| Solo voice / hum | Strong | Strong | Strong |
| Solo piano | Strong | Good | Good |
| Bass line alone | Good | Good | Good |
| Full band mix | Weak (one-instrument model) | Better (separation heritage) | Unverified |
| Live / noisy room | Weak | Unknown | Unknown |
The pattern is consistent: monophonic, clean sources are solved across the board; dense, real-world mixes are where the gaps open up, and where only Basic Pitch's openness lets you see why it failed.
Verdict: which should you trust?
- Trust Basic Pitch when you need to verify or script it. Its accuracy is the only one you can reproduce, and pitch bends survive the conversion. Cost: you run Python, and it expects one clear instrument.
- Trust jukeblocks when your source is a mixed track and you want a web workflow — but go in knowing you are trusting a brand claim, not a number.
- Trust OpenMusic when you already pay for its toolkit and need a quick MIDI among other features; treat its accuracy range as a hopeful upper bound.
No tool is "the accurate one." The accurate choice is the one you measured against your own audio using the rubric above.
FAQ
Can I just believe the "95% accurate" claim? Only if the vendor names the dataset, the metric, and the independent test. OpenMusic names none of those, so no.
Why doesn't anyone publish a fair comparison? Because there is no shared, independently run benchmark for consumer audio-to-MIDI. Each vendor tests on audio it chose. That is exactly why the DIY test in this guide exists.
Is Basic Pitch's MUSDB score real-world? It is real and reproducible, but MUSDB is curated studio material. Expect lower on phone recordings and live rooms.
Do I need to upload my audio to test them? Only the web tools require upload. Basic Pitch runs locally, so it keeps your file on your machine — useful if privacy matters for the test clips.
Bottom line
"Accurate" is not a slogan you can shop for; it is a measurement you have to make. Basic Pitch is the only one of the three whose accuracy you can check yourself, OpenMusic gives a vague but plausible self-reported range, and jukeblocks gives you nothing to verify. Run the five-step test on your own clips and you will know — for your music — which one actually earns the word.
<p><a class="try" href="https://sound2midi.xyz/">Try the free in-browser audio-to-MIDI converter →</a></p>