Its own page describes the output as key and BPM estimates. That is a fair description of what every key and tempo detector produces, including Session Key.

Comparison

Tunebat vs Session™ Key.

Q: What is the difference between Tunebat and Session Key?

Tunebat analyzes audio files you drop into a web page and also carries a database of values for released songs. Session Key is a Mac app that reads the audio already playing on the machine and marks every read with how sure it is.

Q: Does Tunebat work on Windows?

It runs in a web browser, so it is not tied to one operating system. Session Key is a macOS app only.

We make Session™ Key. That is the bias, stated first. Every factual claim about Tunebat on this page comes from Tunebat's own analyzer page, read on August 3, 2026, and it is linked at the bottom. Session™ Key runs on a Mac, macOS 14.4 or later on Apple Silicon.

Tunebat's analyzer reads audio files you drop into a web page; Session™ Key reads the audio your Mac is already playing. Both do the work on your own machine, because Tunebat's page states that its analysis runs inside your browser, so the real difference is not privacy. It is whether you have to stop what you are doing and hand a tool a file.

Which one, by what you are doing

You want the key and tempo of files sitting in a folder: Tunebat. Its page describes gathering the files into a folder, dragging them onto the page, and getting results back in a table. See the analyzer.
You are not on a Mac: Tunebat. It runs in a browser. Session™ Key is a Mac app, macOS 14.4 or later on Apple Silicon.
You do not want to pay anything: Tunebat. Its own plan table lists key detection and BPM detection under the free plan, with ad removal and the sentiment features under Pro.
The music is playing and you want the number now: Session™ Key. There is no file to find, no upload step and no browser tab. It reads what is coming out of the machine.
You are working off a stream, a video or a reference in a tab: Session™ Key. A file-based tool needs a file, and you do not have one.
You want to know when the reading is shaky: Session™ Key. Every read is marked with how sure it is, so a strong one and a rough one never look the same.

They are answering different questions

Tunebat's analyzer page describes its audience directly: DJs interested in harmonic mixing, producers looking to remix songs, and anyone trying to understand their music a little better. That is a library job. You have material, you want it labeled, and you do the labeling in a batch.

Session™ Key is for the other half of the day. The session is running, something is playing, and you need the key and tempo without leaving the thing you are doing.

Neither of those replaces the other. If you only ever need one of them, this page is easy: pick the one that matches the job.

The upload question, answered properly

It would be convenient for us to say that a browser tool sends your unreleased music somewhere. Tunebat's own page says the opposite, and we are not going to pretend otherwise.

Under its own heading for how the tool works, the page states that analysis and calculations are run inside your browser so your files are never sent to another machine. That is on Tunebat's site, in Tunebat's words, and it is the honest answer to the question everyone asks about web analyzers.

So the privacy row is not a row. What remains is the workflow row, and that one is real: dropping files into a page is a stop, and a stop in the middle of a session costs more than the seconds it takes.

What each one is built on

Tunebat is open about its engine. Its page credits technology developed by the Music Technology Group at UPF, and the footer states that the analyzer is powered by Essentia.js and Essentia models licensed from MTG.

The same footer states that the Tunebat music database is powered by the Spotify Web API. That is worth knowing, because the numbers you look up for a released song and the numbers the analyzer produces from your file are not coming from the same place.

Session™ Key is our own engine, running on your Mac. We do not publish what is inside it, and we would rather be judged on how it behaves than on a spec sheet.

Where Session™ Key wins

There is no file step. The audio is already playing. A tool that starts by asking you to find, export or upload something has added work to a moment where you had none.

It works on things that are not files. A stream, a video, a reference in a browser tab, a synth you are playing right now. None of those can be dropped onto a page.

It tells you how sure it is. Confidence is the part almost nobody shows, and it is the difference between a number you can act on and a number you have to check by ear.

It returns nothing when there is nothing to read. A drum loop has no key, and the honest output is an empty one. Why that is.

It stays out of the way. There is no tab to open, no plan to pick and no ads to dismiss.

What each one costs

Prices read on August 3, 2026 and they move, so check both before you decide anything.

Tunebat. Key and BPM detection are listed under the free plan. Analyzer Pro is listed at $7.99 per month, or $2.99 per month billed yearly at $35.88. The page also offers all Tunebat Pro features at $19.99 per month. Source.
Session™ Key. $39 once, no subscription, updates included, up to three Macs. Source.

Can you use both?

Yes, and most people probably should. They cost almost nothing to keep around together and they cover opposite halves of the same question.

Label your sample folder in a batch. Read the room live while you write.

Frequently asked

Does Tunebat upload your music?

Tunebat's analyzer page states that analysis and calculations run inside your browser so your files are never sent to another machine. If that matters to you, read it on their page rather than taking it from us.

Is Tunebat accurate?

Its own page describes what you get back as key and BPM estimates. That is a fair description of what every detector produces, including ours.

What is the difference between Tunebat and Session™ Key?

Tunebat analyzes files you drop into a web page, and it also carries a database of values for released songs. Session™ Key is a Mac app that reads the audio already playing on the machine and marks each read with how sure it is.

Is there a free alternative to Session™ Key?

For handing a file to a web page, Tunebat's own free plan does that. For reading whatever the Mac is already playing, marking how sure each read is, and sending it into the open DAW project, Session™ Key is the tool built for that job.

Does Tunebat work on Windows?

It runs in a browser, so it is not tied to one operating system. Session™ Key is a Mac app only.

Session™ Key

Reads the key and BPM of whatever is playing on your Mac, marks every read with how sure it is, and does the work on the machine so the audio never leaves it.

$39 once, no subscription. Available now for macOS 14.4 or later on Apple Silicon.

Get Session™ Key Compare every option

Tunebat alternatives for producers Mixed In Key vs Session™ Key Why detection returns the wrong key All the answers

Sources, read August 3, 2026

tunebat.com/Analyzer: the stated audience, the folder and drag-and-drop workflow, the results table, the wording that analysis runs inside your browser and files are never sent to another machine, the description of results as key and BPM estimates, the credit to the Music Technology Group at UPF, the Essentia.js and Essentia model credit, the Spotify Web API credit for the database, the free and Pro plan table, and the listed prices.
session.am/session-key: $39 once, no subscription, up to three Macs, on-device detection, and that it is available now.