Audio tools for iPhone, iPad, Mac & Android — and for your family!
RSJB is an independent Brazilian studio that builds apps focused on music and family — no ads, no tracking!
Our apps
Our apps, one philosophy.
Tonic Synth
On the App StoreThree layers, eight sound engines per layer, eight analog filters and a full effects rack — in your pocket, standalone or inside your DAW.
Learn more →Tonic FX
On the App Store34 effects you build, reorder and play live: drive, modulation, voice, delay, reverb, EQ and dynamics.
Learn more →Tonic EP
Coming soonTwo electric pianos calculated note by note, with no samples: tine and reed, a suitcase amp with stereo tremolo and a 16-effect rack.
Learn more →NL4 Editor
Coming soonA panel with all 86 parameters, reading the keyboard's banks, organizing and writing them with verification, sound conversion and a stage setlist.
Learn more →NX Editor
Coming soonAll four Zones of your keyboard on one screen — sounds, effects, levels and six colour scenes that switch without a cut, live.
Learn more →Rsf2
In storesMerge, split and reorder presets — byte-exact and on-device.
Learn more →RDX
On the App StoreOpen, preview and build .syx banks from classic FM synths.
Learn more →REXS
On the App StoreOrganize, play and convert your .exs instruments to SoundFont — without Logic.
Learn more →Tonic Filter
Coming soonTonic's filter section in one effect app: eight analog characters and an envelope that listens.
Learn more →In the press
A news post on Tonic 2 — a three-layer synth for iPhone, iPad and Mac: 3D wavetables, a Vector XY pad, a 12-mode arpeggiator and eight sound models per layer, standalone and AU/AUv3.
Read the article →A feature on Tonic — an analog-modeling synth with eight synthesis engines, three layers, analog filters and AUv3.
Read the article →Focused tools, no distractions
Audio apps to create, organize and play your music — no ads, no tracking. Crafted with care, in Brazil.