App Overview

MidiStep icon

MidiStep

4Pockets.com · Music

MidiStep is a powerful and inspirational polyphonic step sequencer, and a dream for lovers of complex rhythms and generative music creation tools

$8.99 · In-app purchases

PRICE
$8.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
5.0
22 ratings · Top 5%

Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.

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What's included18 files

A product spec, phased build plan, differentiation notes, and screen references.

  • START_HERE
  • AGENTS
  • EVIDENCE
  • SPEC
  • BUILD_PLAN
  • DIFFERENTIATION
  • skills/
  • screens/
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Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.

Feature spec

Goal: Send a clear invoice after finishing a job.

  • Add a client, line items, a due date, and payment instructions.
  • Preview the total before exporting a PDF.
  • Keep an editable draft if export fails.

Screen plan

Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.

States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.

Differentiate and validate

Hypothesis: Contractors need faster repeat invoices more than more templates.

First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.

The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.

Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.

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Quick prompt

> SELECT BUILD PLATFORM:

Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.

// RORK SYSTEM PROMPT
Rork plan preview for MidiStep: map the core Music workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
            

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Opportunities

AI-GENERATED OPPORTUNITY HYPOTHESES

These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.

Hypothesis 1

Expand editing capabilities with advanced tools and effects.

Assumption to check: Limited MIDI editing features compared to professional software

Validate with people who use this workflow before building.

Hypothesis 2

Implement guided tutorials or onboarding for better user experience.

Assumption to check: Steep learning curve for new users

Validate with people who use this workflow before building.

Hypothesis 3

Enable MIDI file sharing across different platforms and devices.

Assumption to check: No cross-platform support for MIDI files

Validate with people who use this workflow before building.

Hypothesis 4

Offer more in-app purchases for sound packs and instruments.

Assumption to check: Limited sound libraries

Validate with people who use this workflow before building.

App evidence

Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.

App Store description

MidiStep is a powerful and inspirational polyphonic step sequencer, and a dream for lovers of complex rhythms and generative music creation tools. The program uses sophisticated, user-controlled randomization to generate notes with a variety of parameters, including note values, note length, chords, patterns, velocity, gate, dividers, repeats, swing, and many more. You have complete control over what, when, and how much is randomized on a step-by-step basis. You can easily create patterns that have little to no variation, patterns that maintain a recognizable pattern but have some degree of variations to the notes, velocity, etc., all the way to patterns with extreme randomness with every pass – the degree of randomization is completely under your control for every parameter and for every step of a pattern. Features include per-step polyphonic chord playback, variable step sequence lengths for all parameters such as pitch, octave, velocity, note duration, beat divisions etc, and the capability to create multiple patterns which can be linked together in various ways. MidiStep also features 8 additional modulation lanes with independent play speeds. These can be used to automate parameters within your favourite synths. MidiStep uses sophisticated randomization settings for note values, note lengths, velocity, gate, dividers, repeats, swing, pitch bend and modulation. In addition, by setting different cycle lengths, step skips, step repeats, jumps, rewinds, cursor positions, pattern jumps, octave shifts, and many other parameters, you can create an infinite number of non-repeating sequences. The degree and types of randomizations for each of these parameters is up to you! Aleatoric music, also known as chance music, allows you to create patterns and entire compositions with user-controlled randomisation. The word 'aleatory' is derived from the Latin word 'alea' meaning dice. MidiStep allows you to turn on/off randomisation on a stepwise basis for almost all parameters, set the percent probability that the randomisation will occur, set min/max values, set exactly which parameters will be randomized, etc. The exact realization of the music will vary with each pass of the sequence, resulting in unique and captivating aleatoric renditions. All randomization controls can be modified in real-time. Features include: •Each of the 16 sequences can have unlimited types and degrees of randomness that you control. •8 independent sequencer lanes: Notes, Chords, Octaves, Velocity, Gate, Divider, Repeat, Delay. •8 independent Modulation sequencer lanes. •16 Patterns and 4 types of pattern switching, independent for each pattern. •Up to 16 steps per pattern, 16 patterns, and 16 cycles per pattern for a maximum sequence length of 4096 notes. •Independent sequencer length (1–16 steps) for each of the 16 lanes. •A Master step cursor independent of all other lanes. •Independent randomization parameters for each of the 16 lanes, with probability, min/max values, default values, skips, repeats, etc. •Unlimited variety of sequences, from slight variation to wildly different sequences on every pass. •126 scales and 126 chords – in every key, along with a scale and chord editor for you to create your own. •Chord complexity for 2–8 note chords, with notes specified or randomly generated. •Chord Articulation options – Block chords, Strum up/down, Arp up/down – with accent, length, speed, and random note order parameters. •Master lane and Chord lane previews. •Pattern Creator - automatic melody, chord, bass and drum backing. •Auto-scroll chord lane. •7-octave range for notes and chords (from C1–C8), with static and random octave offsets. •11 note lengths – from 1/32 note to 4 full measures, plus ties across notes, rests, repeated notes, and delays. •Two types of Swing with adjustable offset. •Humanize settings for note velocity and note timing. •Transposition of sequences using a keyboard – mono for single notes, and poly for chords.

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Build scope

Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.

Define the first version

Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.

Set boundaries

Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.

Check the hard parts

Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.

SUGGESTED BUILD STACK
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BUILD KIT DIFFICULTY
Advanced

From the Build Kit assessment.

A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.