@rsjb_appFollow

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

Three tools, one philosophy.

Tonic Synth

On the App Store

Three oscillators with many sound generators, many filter emulations, an arpeggiator, a wavetable editor and an effects rack — standalone and AUv3.

Learn more →

Tonic FX

On the App Store

A complete effects rack you build and reorder: drive, modulation, delay, reverb, EQ and dynamics.

Learn more →

Tonic Filter

Coming soon

Tonic's filter section in one effect app: eight analog characters and an envelope that listens.

Learn more →

Rsf2

In stores

Merge, split and reorder presets — byte-exact and on-device.

Learn more →

RDX

On the App Store

Open, preview and build .syx banks from classic FM synths.

Learn more →

REXS

On the App Store

Organize, play and convert your .exs instruments to SoundFont — without Logic.

Learn more →

In the press

AudiofanzineFrench music & audio platform

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 →
AMAZONA.deGerman synth magazine

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.