43 Electro Swing writes complete electro swing songs and plays them with a band. Press write and you get a whole record: old verses heard through a gramophone, builds that open the sound up, and club drops with a four-on-the-floor kick under the band and the whole band pumping around it — then a solo, a break or a big-band shout, and an ending: a turntable brake, a big-band button, or the record fading back to 1937. The band is two gypsy-jazz rhythm guitars playing la pompe, a lead on clarinet, trumpet, muted trumpet, alto sax or guitar, a three-piece horn section, upright and sub bass, keys, a swing kit and a producer's house beat. The guitar and the kit are real recordings; the horns, clarinet and bass come from an FM engine that blows and scoops and slurs like players do. All of it ships inside the app, so it works with no network at all. The songs come from chaos maths. A Lorenz attractor draws the melody and a logistic map shades the drummer and the comping, so no two bars need be alike. Chaos on its own is noise, so a small model filters it: it is rewarded for swinging intervals and learns as it writes. The CHAOS / TASTE slider decides how much say each one gets. Eleven styles, and each one is a whole band: its changes, its drummer, its tempo range and how hard it swings. Electro Swing, Hot Club House, Big Band Boogie, Jump Blues, Noir Swing, Swing Hop, Balkan Beats, Charleston, Cabaret Lounge, Electro Dixie and Swing Step. Tick STYLE LOADS RIG and each style brings its own sound. The sound is half the record. Four channels — bass, rhythm guitar, horns and lead guitar — each with a voicing, a tone stack and a resonator: a gypsy-jazz guitar body, a speaker, a gramophone horn or a straight ribbon microphone. Seven one-click rigs, from Hot Club to Warehouse. Effects for the record and the club: sidechain pump, vinyl crackle, gramophone, tape wow, chorus, tremolo and spring reverb. Every song is built from its seed. Write the seed down and you can have that exact song again, note for note. A seed from the browser version rebuilds the same song here. You can play over it, too. The pads are the notes of the song's key rather than a piano keyboard, so nothing you touch is wrong, and the sixteen-step lane swings with the song and follows your host. Both play any of ten instruments through its own channel and out on its MIDI channel. Turn on RADIO and it keeps playing, picking a new style, key, scale and tempo for every song. You also get: • 11 styles, 14 scales, 12 keys, tempo and density • 15 voicings, 6 resonators, 7 rigs and 7 effects • 8 keyboard voices, from upright piano and vibraphone to accordion and bandoneon • Sampled or synthesised drum kit, switchable; brushes always synthesised • Seven-part mixer with a meter on every part • MIDI in, so your keyboard plays whichever instrument you have selected • Export a MIDI file, a WAV mix, or stems — one WAV per part (in the app; in a host you record the audio there) • A note and a MIDI channel for every drum and every house-beat hit • UI scale, so the panel is not tiny on a big iPad • Live spectrum and waveform, and the chaos engine drawn as it runs Two Audio Units, an instrument and a MIDI processor. Each part sends on its own MIDI channel and every drum has a note and a channel of its own, so one instance can drive a rack of them. The MIDI version passes your keyboard through. Both follow your host's tempo and transport, and one install registers both. The app is free and nothing in it is held back. Using the Audio Units inside other apps is a one-time purchase, and each AUv3 session plays for two minutes first so you can try them properly. No account, no ads, no subscription. Works offline. Samples: Karoryfer Emilyguitar and Big Rusty Drums, and two voices from the Versilian Community Sample Library, all CC0.