Billie Tracker vs Strange Loop
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Billie Tracker
Create music with a powerful groovebox featuring a step sequencer, synthesizers, and a sampler. Arrange patterns into songs, shape unique sounds, and export your finished tracks. Designed for intuitive music production on mobile devices.
- Step sequencer for notes and instruments
- Shapeable synth instruments
- In-app sampler for recording sounds
- Mixer with per-track controls
- Song arrangement and export options
- Hardware controller support
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Billie Tracker is a groovebox: a step sequencer, synth instruments, a sampler and a mixer, built as one instrument for your phone or tablet. You write music in a grid. Notes go into patterns, patterns chain into sections, and sections line up into a song, so a full track grows out of small pieces you can reuse and rearrange. Trackers have worked this way for decades. If you have used one, this will feel like home. If you haven't, a built-in tutorial walks you through your first pattern, and every screen has help one key away. It is not tied to one sound. Shape the synths from clean tones to heavy drive, sample anything and play it back as an instrument, and make whatever you want to make: techno, ambient, hip hop, pop, or the 8-bit styles trackers are known for. Rows hold up to eight notes, not just one. Every instrument is polyphonic, so a chord goes into the grid the same way a single note does. Hold one on a MIDI keyboard and it lands across the row's note lanes, quantized and in key. What you get: - A step sequencer for notes, instruments, volume and effects, with chains and a song view for arrangement - Up to eight note lanes on every row, so chords are typed in like single notes, on any instrument - Synth instruments you can shape: timbre, color, filter, drive, envelopes and LFOs - A sampler that records straight into the app, so your own sounds sit next to the synths - A mixer with per-track levels and sends - BOUNCE and STEMS, so a finished song leaves the app as audio - Bundles: a song and every sample it uses travel as one file - A control surface built for tracker speed. Hold one key, press another, fast. Rearrange the layout to fit your hands, or plug in a hardware keyboard or game controller - Themes, KEY and SCALE settings, and a HELP key that explains whatever you are looking at Your songs are ordinary files. There is no account and nothing to sign into. Send a song to a friend, email one to yourself, or move it around in your file manager. Nothing is uploaded to us and nothing is locked to us. Billie Tracker is made by Billie Workers' Co-op. The people using it steer what gets built, and the Discord is the fastest way to reach us.
Strange Loop
This app generates unique melodies using chaos theory and music theory principles. Save your creations as MIDI files or use them as an AUV3 plugin. You can influence the sound by interacting directly with the visual representation of the attractors.
- Melody generation using Lorenz attractors
- Markov policy for taste customization
- Save melodies as MIDI
- AUV3 plugin for instruments/MIDI processing
- Interactive attractor influence via painting
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Strange Loop writes its own music. Three coupled Lorenz attractors drive the piece — one proposes pitch, one shapes rhythm, one wanders the emotional plane. A Markov policy then decides what actually plays, learning from its own output and rewarding intervals that sound consonant. Chaos proposes, the policy disposes. Slide BLEND to choose who wins. Nothing is pre-recorded and nothing loops. Every run is new. PAINT ON THE MATHS Both scopes are paintable. Draw on the attractor and the trajectory bends toward what you drew and lingers there, pulling the melody into those pitches. Draw on the mood pad and the feeling follows your strokes — brightening the harmony, lifting the register, pushing the tempo. Set how hard the ink leans, how big the brush is, and how long it lasts before it fades. WHAT YOU GET • 26 scales — major and minor modes, pentatonics, blues, whole tone, harmonic and melodic minor, altered, both octatonics, and folk scales from Japan, China, Egypt, Spain, Arabia and Hungary • 7 accompaniment styles — chaos grooves, jazz comping with walking bass, stride piano, Alberti bass, classical, arpeggios, ambient rolls • A sampled grand piano plus synthesised voices: soft piano, glass, strings, FM bell, AM organ, pluck, fat saw and more • 6 moods on a valence/arousal plane, from serene to tense, driving chord quality, register, tempo and note length • Live scopes — the attractors, the note-probability distribution the engine is sampling from, and the mood point, all drawn in real time • Deep control: key, scale, tempo, chaos rho, rhythm spread, grace notes, chord-tone pull, softmax temperature, per-track mixer • Record a take and export it as a standard MIDI file to the Files app — melody, chords and bass on separate tracks TWO AUDIO UNITS Strange Loop ships as an instrument AUv3 and as a MIDI processor AUv3, so it can either play its own sounds or sequence any other instrument in your host. Melody, chords and bass each send on their own MIDI channel, so one instance can drive three different instruments. Both Audio Units follow your host's transport and tempo — hit play in AUM, GarageBand, Logic, Cubasis or Zenbeats and it locks to the grid. One install registers both. CREDITS Sampled piano: Salamander Grand Piano by Alexander Holm (CC BY 3.0).
Screenshots
Verdict
The clearest difference is in-app purchases: Billie Tracker at none against Strange Loop's 1. On price, rating, review sentiment and ratings volume there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Strange Loop sells 1 one-off in-app purchase. Billie Tracker asks for nothing beyond the download.
On the App Store both sit at effectively the same score — 5.0 for Billie Tracker against 5.0 for Strange Loop. Both are backed by a comparable volume of ratings — 5 and 9 respectively. Written reviews split almost evenly too, at 100% and 100% positive.
Billie Tracker ships an update every 2 days, Strange Loop every 4 days. The most recent releases landed on October 17, 2026 and October 31, 2026 respectively.
| Parameter | Billie Tracker | Strange Loop |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (5 ratings) | 5.0 (9 ratings) |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| Number of ratings | 5 | 9 — better |
| Update frequency | Every 2 days — better | Every 4 days |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Free with in-app purchases |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod, Mac — better |
| Requires iOS | 15.1 | 15.0 — better |
| Further details — not scored | ||
| Size | 57 MB | 23 MB |
| Age rating | 4+ | 4+ |
| Developer | Billie Cooperative | Soft Brew Mobile |
Customer experience
Billie Tracker
Strange Loop
In-app purchases
Billie Tracker
No in-app purchases
Strange Loop
- Unlock AUV3 Plugin$2.99
Questions
Is Billie Tracker free?
Is Strange Loop free?
Which has better reviews, Billie Tracker or Strange Loop?
Do Billie Tracker or Strange Loop have ads?
Which is updated more often, Billie Tracker or Strange Loop?
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