El Eje Player is a native macOS app that organizes, understands, and plays Golden-Age tango the way a DJ actually works a milonga. It reads the music — key, tempo, lyrics, orchestra — handles fragile 1940s transfers next to modern stereo without flinching, and keeps everything offline on your own Mac. It's also where you learn the music — tango terminology, orchestra and singer history, and ear-training all live in the same app. Not a club player with a tango skin: a tool shaped around the floor.
📘 Read the step-by-step User Guide →
A library that thinks in tango
Organized the way you program a night — not an alphabetical dump of files.
Orchestra & singer aware
Music, Cortinas, Tandas, and Playlists — your collection grouped by orchestra in canonical order, with singers and cortinas kept where they belong.
Best version, automatically
Five transfers of the same recording? El Eje groups them and surfaces the best one, so your tandas stay clean and consistent.
Search that knows Spanish
Accent- and case-insensitive search folds D'Arienzo, Pugliese, and every name in between — type it however you like and still find it.
Built for the booth
The controls you reach for mid-tanda, where reliability matters most.
Separate cue & master
Pre-listen in your headphones while the room hears the master — route cue and main output to different audio devices.
Pitch-preserving tempo
Nudge tempo in 1% steps (0.7–1.3×) without changing pitch. Cue points and markers stay frame-accurate at any speed.
Per-track EQ + presets
Shape each transfer for the room and save the EQ with the song — reach for a preset or dial it in by hand.
Cue points & timeline
Set cues and timeline markers; the waveform shows exactly where the music turns, so entrances and finales land every time.
Even tanda gaps, automatically
Old transfers carry wildly different amounts of silence. El Eje finds each track's real first and last sound, so the pause between songs in a tanda stays even — no dead air, no clipped endings.
Mono & modern, side by side
Plays fragile 1940s mono transfers and modern stereo seamlessly in the same set — no format crashes, no surprises.
Full metadata editing
Fix titles, orchestras, singers, years, and artwork in place — changes propagate across every version of a recording.
It knows the music
Analysis tuned for tango, running locally on your Mac.
Musical key detection
Native key detection tuned for tango, shown in Open Key notation. Detect a whole playlist at once; imported keys are never overwritten.
BPM detection
Automatic BPM for every track — in bulk or one at a time — so energy and tanda pacing are always in view.
Tanda builder
Drag tracks into tandas and get a warning the moment an orchestra, era, or genre doesn't belong — build the arc of a night with confidence.
A tango learning suite, built in
Words, history, and ear-training in the same app — one place to go deeper into the music, not a pile of separate tools or browser tabs.
Synced lyrics + translation
Full lyrics that scroll with the music, with the original Spanish and a line-by-line translation side by side.
Lunfardo thesaurus
A built-in tango/lunfardo dictionary — open a word to see its sense and literal meaning, and truly know what you're playing.
An illustrated tango encyclopedia
Hundreds of illustrated articles — orchestras, singers, poets & composers, instrumentalists and dancers, plus tango archetypes, films, and a year-by-year timeline — with bios, key facts, and photos. Click an orchestra or singer name anywhere in the app to jump straight to its article.
Ear-training flashcards
Spaced-repetition decks for the orchestras and singers, built from reference scholarship — recall the sound, then reveal.
Going further
The deeper, more experimental tools that make El Eje one of a kind.
Singer voice models experimental
An on-device engine that can restore or transform vocals on degraded 1940s recordings using per-singer AI voice models (so-vits-svc / kNN-VC), trained from your own library.
Performance video sync
Attach and align a performance video to a track, so you can study how a recording actually moves dancers on the floor.
Traktor import
Bring your Traktor collection straight in — keys, BPM, and metadata read directly from
collection.nml.
How it works
El Eje Player runs entirely on your Mac. Your audio files never move and never leave the machine — the app reads them in place and stores its own data (lyrics, metadata, collections, EQ, cues) in your Application Support folder. All analysis — key, BPM, lyric matching, even the singer voice models — runs locally and offline, so you can rely on it in a venue with no internet.
It's built in native SwiftUI for speed and a real Mac feel (no Electron), and it's designed to stay portable: a single self-contained app you can carry to any gig.
In active development. Features above are live in the current private build; the roadmap continues to grow. Want to try it or shape what comes next? Request early access.
El Eje for Chrome companion · in development
A free browser companion that carries your tango library onto the web — fully offline, no account, nothing leaves your browser.
Reference any recording
A side panel that looks up any track — orchestra, singer, year, key, BPM, mood, and lyrics with translation — and shows other recordings of the same song. Right-click any title on the web to look it up.
Follow lyrics on YouTube
Watching a tango on YouTube? Spanish + English follow-along lyrics appear right on the page, with a “pick the right version” corrector when titles are ambiguous.
Offline & private
The whole ~24k-recording library snapshot lives inside the extension — it works with no internet, stores nothing, and tracks nothing.
Built on the same library as El Eje Player. See the full El Eje for Chrome page →
More tools for DJs
Browser-based companions you can use right now.
Tanda Builder →
Plan and audition tandas by orchestra, era, and energy.
EQ Lab →
Hear what equalization does to a transfer before you commit.
All tools →
The full set of software and guides for tango DJs.
Try El Eje Player
Join the private beta, or tell me what would make your sets better — the roadmap is shaped by working DJs.