Caustic Development Timeline 

Pre‑Version 1.0 — Origins (Pre‑2010)

Prototype Development  

Caustic began as a subtractive synthesizer prototype created by Rej while learning synthesis concepts. The early UI was described as “pretty ugly,” and the prototype existed long before Caustic became a full workstation.

Naming History  

The app was originally titled “No Good Reason” as a self‑deprecating nod to Propellerhead Reason. A friend later suggested the name “Caustic”—a cool‑sounding chemical term similar to “acid,” but less obvious—aligning with Rej’s desire not to force a specific musical style.

Version 1.0 — First Public Release (May–June 2010)

Platform Milestone  

Caustic debuts on the Android Market. Early in‑app purchase receipts confirm this era.

Core Features

• SubSynth (subtractive synthesizer)

• Early PCMSynth implementations (PCMSynth 1 & 2)

• Fixed rack layout with a small set of machines

• Pattern‑based sequencer

• Rack‑mount synthesizer/sampler workflow

Developer Notes  

Rej discovered TB‑303 example code and “squeezed in” a new BassLine‑style synth during development.

Versions 1.1–1.2 — Undocumented Transition (2010–2011)

A data gap exists between 1.0 and 1.3. No detailed records survive for versions 1.1 or 1.2.

Version 1.3 — Refinement Era (2011)

Platform Milestone  

Continued distribution on the Android Market.

Core Features

• Updated SubSynth

• Updated PCMSynth

Developer Notes  

Rej noted that this version used less graphics memory than later builds.

Version 2.0 — Expansion Era (2011–2012)

Platform Milestone  

Introduction of the Manual Licensing Era, where users received unlock keys via email.

Core Features

• BassLine (303‑style synth)

• BeatBox (8‑channel drum machine)

• Redesigned PCMSynth

Workflow Changes

• Pattern‑based logic expanded

• Early automation introduced

Developer Notes  

BlackBerry/PlayBook builds used native C/C++ hooks to avoid heavy framework overhead.

Version 2.1 Beta Cycle (2012)

2.1.0 Beta 1

Platform Milestone  

Android testing build.

Workflow Changes

• Standardized pattern editor

• Vertical (portrait) multi‑machine layout

• Customizable keyboard and piano roll sizes

• USB‑MIDI controller support (Android 3.1+)

• WAV support (8–64‑bit, mono/stereo)

• Exponential envelope mapping

• Ability to trim measures

Known Issues

• Crash on first run after extracting demo content

• Piano roll limited to 16th notes; no triplets

2.1.0 Beta 2 — 4 November 2012

Core Features

• Latency selection (1.5ms / 5ms / 24ms / 93ms)

Workflow Changes

• Windows latency reduced to ~6ms

• Lasso select fixed

• Multi‑select button highlighting

2.1.0 Beta 3 — 6 November 2012

Workflow Changes

• Piano roll zoom beyond 16th notes

• Triplet support added

Bug Fixes

• Stuck BassLine notes resolved

2.1.0 Beta 4

Workflow Changes

• Corrected pattern sizing for long patterns (>1 measure)

• Nudge notes and shuffle bypass mentioned

Bug Fixes

• Fixes for playback issues at pattern boundaries

2.1 Release Candidate (RC1–3) — 13 November 2012

Workflow Changes

• Testing note grid snapping

• Removal of play‑cursor smoothing

Version 2.1.0 — Official Release (12 December 2012)

Platform Milestones

• Transition to Google Play licensing

• USB‑MIDI support (Android 3.1+)

• Windows latency optimized (~6ms)

Core Features

• Parametric EQ

Version 2.1.1 — Maintenance Update (2013)

Workflow Changes

• Stability fixes for market‑release issues

Version 2.1.2 — Stability/Rollback Release (2013)

Developer Notes  

Provided as a stable fallback for users experiencing issues with Version 3.

Version 3.0 Alpha / RC — Mid–Late 2013

Core Features

• Rack expanded to 14 machine slots

• Introduction of 10 synth types: Modular, FM Synth, PadSynth, 8‑Bit Synth, Vocoder, KSSynth, and others

Workflow Changes

• Dedicated mastering section

• Automation editing

• Mic capture for sampling

• Keyboard note recording

• MIDI import

Version 3.0.0 — Official Release (14 December 2013)

Platform Milestones

• Google Play release

• iOS launch (iPad + iPhone)

• Free standalone Windows and macOS versions

Core Features

• Fully modular rack

• WAV import

• Per‑machine and per‑bus effects racks

• Song Mode for pattern arrangement

Developer Notes  

Sound engine switched to 32‑bit fixed point to match Modular’s engine.

Version 3.0.1 / 3.0.2 — BlackBerry / PlayBook (Late 2013–Early 2014)

Platform Milestone  

BlackBerry World release.

Workflow Changes

• 3.0.2 fixed a WiFi‑related launch crash caused by FTP server initialization.

Version 3.1.0 — iOS Expansion (17 May 2014)

Platform Milestones

• Audiobus 2

• Inter‑App Audio (IAA)

• AudioShare integration

Core Features

• Modular: Machine Input module

• Modular: K35 Low‑Pass filter

Workflow Changes

• Automation added to iOS version

Version 3.1.1 / 3.1.2 — Maintenance (2014)

Workflow Changes

• 3.1.2 introduced stuttering when recording vocals during playback on some devices

Version 3.2 Beta Cycle (2015–2016)

Core Features

• Beta 3: c‑sfxr generator added

• Beta 8: SawSynth introduced

Workflow Changes

• Pink (粉) symbol used to mark 3.2‑compatible presets

Known Issues

• Stereo imaging destruction in certain frequency ranges

Version 3.2.0 — Official Release (1 February 2017)

Platform Milestones  

Standardized target for modern Android devices.

Core Features

• SawSynth

• Four new effects (including bottom‑row effects)

• Stereo sample support for PCMSynth and BeatBox

• High‑quality band‑limited waveforms for SubSynth

Workflow Changes

• Expanded time signatures (3/4, 4/4, 5/4, 6/4, 7/4)

• Keyboard scale assistant

• “Merge rack to instrument” tool

Developer Notes  

Rej stated the official release was nearly identical to Beta 8 except for bug fixes.

Introduced a new state‑variable filter.

Version 3.2.1 — Maintenance Release (2017)

Workflow Changes

• Finalized stereo rack functionality

Version 3.2.2 — 64‑bit Recompile (14 December 2025)

Platform Milestones

• Sideloadable APK for Android 11–16

• Native 64‑bit support to bypass Android 14+ restrictions

Workflow Changes

• Full 64‑bit rebuild

• “Nuclear option” file handling (full storage access)

• Unlocker APK no longer required; saving/exporting enabled natively

Version 3.2.2 — Bugfix Update (12 January 2026)

Workflow Changes

• KSSynth damping‑at‑100% crash fixed

• Sample Editor bug fixes

Post‑3.2.2 Era (2018–2026)

Missing Versions  

References exist to planned versions 3.3 and 3.4.

A user claim mentions 3.5 as the final version, but no official notes survive.

The Silent Years (2018–2023)  

No public releases or updates.

2024 Delisting  

Rej deleted his Google Play developer account due to administrative issues and low revenue (~$40/month), removing Caustic from the Play Store.