Key, BPM & energy
Camelot key
JUST PLAY listens to each track and works out its musical key, shown the way DJs read it: a number and a letter, like 8A or 5B (the "Camelot" wheel). Tracks whose numbers are the same or next-door tend to sound good played together. It's worked out on your own computer — no internet, no account.
BPM
The tempo, in beats per minute — measured automatically when a track is added.
Energy
A 1–10 score for how intense a track feels. Ambient sits low; peak-time hard techno sits high. Handy for building a set from warm-up to peak.
Harmonic Sort
Drop a pile of tracks in and JUST PLAY can reorder them into a set that flows — weighing key, tempo, energy and groove together, not just one of them. A running start on any set.
Pre-Cue Finder — audition on headphones
A dedicated, keyboard-first window for finding the next track. Browse your whole library — folders and playlists both — with the same analysis columns as the queue: Camelot key, BPM, energy and the groove and vibe fields. Land on a track and it plays instantly on your headphones, while your set keeps playing to the room.
If your headphones are a separate device, the cue plays only there. If you're on a single output, JUST PLAY ducks the main sound while you cue and brings it back when you're done — and if you're streaming, the broadcast is never touched. Nothing you audition ever reaches the dancefloor by accident.
Filter to the right track
The filter tab narrows a big folder fast: search by name or artist, click a Camelot key wheel to keep only harmonically-compatible keys (the neighbours are one tap away), and drag range sliders for BPM, energy and the vibe fields.
Right-click a folder or playlist
Add to list drops the whole folder or playlist onto the end of your JUST PLAY queue; Open playlist loads it as your set (it asks first if you'd lose the current one); and Refresh re-reads it from disk. Opening a playlist to pre-cue it is the elegant way to line up your next set.
Fits what's playing
One click narrows the list to what would actually mix with the track on air: the playing key plus its harmonic neighbours, a ±3 BPM window, and energy from one step below upward. It works by moving the filters you can see — the key wheel lights up, the sliders move — so you can widen any of it by hand. A button whose reasoning you can't see is one you stop trusting mid-gig.
The library index — searching deeper
By default the finder reads one folder at a time, straight off the disk. Turn on Keep an index of this library in the finder settings and press Scan library once, and three things open up: Include subfolders searches everything below the folder you're standing in, standing above your sets filters across all the playlists under it at once (a track in five sets is one row, and the panel tells you which five), and a big folder paints the instant you step into it instead of after the last tag has been read.
The index is built on this computer, from the tags already in your files, and it lives in your user profile — nothing is written next to your music. That is also why two machines sharing one NAS both stay current without a database between them: whichever one analyses a track first writes the result into the file, and the other reads it back.
It is opt-in in the strict sense: if you never scan, no index file is created at all. And the index can't hide a track from you — files it has never seen are still listed, with blank columns, and one that has gone missing is flagged rather than quietly dropped. Where the index is needed and isn't there, the control that needs it is disabled with the reason written on it, never left as a bare grey button.
A · B · C column views
The track list can show different columns depending on what you're doing. A, B and C are three saved layouts you flip between with one click — each remembers its own columns. For example: A for mixing (Genre, BPM, Key, Energy), B for loudness (BPM, Gain, LUFS, Key), C for whatever you like. Click any column heading to sort by it, and right-click the A / B / C switch to choose which columns that view shows.
The Sound panel — shaping your sound
JUST PLAY has a small, honest set of tone tools on the output. Leave them alone and the sound passes through untouched. Reach for them when a track needs help.
EQ (Low / Mid / High)
A simple three-band tone control. Boost or cut the lows, mids and highs. Flat = no change.
TILT
Every track is mixed a little differently — some too bright and harsh, some dull and muddy. TILT gently leans the overall tone toward a pleasing reference balance (the gentle high-to-low slope most well-made music follows). At 0 it does nothing; turn it up and a harsh track calms down while a dull one opens up — and it adapts to each track on its own. Think of it as a one-knob mastering assistant.
PUNCH
PUNCH sharpens the very start of each drum hit — the attack of the kick and snare. A little makes a track feel tighter and more alive; too much starts to sound clicky. At 0 it's off.
Limiter / Maximizer
The safety net and the loudness knob, right at the end. It catches the loudest peaks so nothing distorts, measured to the broadcast true-peak standard with the ceiling kept just under the edge. Four settings trade loudness for dynamics: Off (untouched), Soft (a gentle catch that keeps the punch), Club (louder and denser), Loud (pushes hardest). Important: it only ever turns peaks DOWN — never the cheap trick of shoving everything up, which just adds distortion and ear-fatigue.
Genre presets
One-click starting points — Electronic, Hard, Rock, and Neutral (flat). Each sets the whole panel to a sensible place for that kind of music. Fully editable, and you can save your own — right-click a preset to replace it with your current settings, rename it, or delete it.
Loudness normalisation
Different tracks are mastered at different loudness, so without help you're forever nudging the volume. Normalisation makes them all sit at one steady level. Pick Quiet, Normal or Loud. It doesn't change your files, and it won't let a track distort.
Crossfade & play modes
On auto-advance JUST PLAY can crossfade one track into the next — an equal-power blend so the level stays steady through the transition. Pick the length (off, 2, 4 or 8 seconds). Alongside it the usual transport modes: shuffle (a bag-with-history, so nothing repeats until the bag is empty), repeat, and a consume mode that drops each track from the queue as it plays.
Your files are the memory
When you ask — and only then — JUST PLAY writes the detected key, BPM and energy into each file's own tags. The analysis then travels with the track, and other apps can read it. Every change is undoable. Close the app and your queue is gone again — nothing is ever written into your music folders except the tracks' own tags.
The one thing JUST PLAY can keep is the library index, and only because you asked for it: it lives in your user profile, it is built from those same tags, and it is off until you switch it on.
Streaming from the player
JUST PLAY can broadcast your set straight to an Icecast server, with a clear on-air light, several saved server profiles, and MP3 or Opus. The streaming panel splits into Server / Quality / Station tabs; the Station tab carries your station's website, genre, description and a public-directory toggle into the stream — functionally the same station metadata as JUST STREAM. For a dedicated broadcaster with app-capture, see JUST STREAM.
Compact view
Shrink JUST PLAY to a compact view — just the spinning vinyl, cover art and the transport controls — for when you want it small and out of the way. One click switches between the compact and the full view.
Menus & right-click — where the shortcuts hide
To keep the main window calm, a lot of JUST PLAY's power lives in right-click menus and the "…" button rather than on-screen buttons. Here's what's where:
Right-click a track
The per-track menu. Analyse it (or re-analyse); write or keep each detected value on its own — BPM, Key, Energy — or restore the file's original; write all tags or just fill in what's missing; undo the last write; or remove the track from the queue.
The "…" button (bottom-right)
Actions for the whole list: Harmonic Sort, Remove duplicates, Clear list, Write tags to all, and a Remove played tracks toggle. Plus playlists — Save, Save as…, Open playlist…, and Transfer ▸ to bundle the whole set as a ZIP or copy it into a folder (straight onto a USB stick).
Right-click the A / B / C switch
Choose which columns that view shows — Genre, BPM, Key, Energy, Gain, LUFS, Duration, Like.
Right-click the radio icon (top bar)
Go on air without opening the streaming panel: connect to a saved station, disconnect, add a radio, or jump to the streaming settings.
Right-click a Sound preset
Replace it with your current settings, rename it, or delete it.
Six themes
Aurora, Sunset, Midnight, Onyx, Neon and Hardcore — from soft aurora to pitch-black to all-black-with-red. Swap live, no restart; the app icon even repaints to match.