App Overview

WretchUp icon

WretchUp

MoMinstruments GbR · Music

An effect instrument anyone can play - sonic anarchy in the palm of your hand.

$4.99 · In-app purchases

PRICE
$4.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
3.1
9 ratings · Below Average

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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Build Kit

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A product spec, screen plans, and build steps for your coding agent.

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What's included15 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 WretchUp: 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

Focus on building partnerships with music labels for a larger library.

Assumption to check: Limited song library compared to competitors

Validate with people who use this workflow before building.

Hypothesis 2

Implement a more straightforward navigation system and onboarding process.

Assumption to check: User interface can be confusing

Validate with people who use this workflow before building.

Hypothesis 3

Ensure robust background playback support and user control.

Assumption to check: Playback issues in the background

Validate with people who use this workflow before building.

Hypothesis 4

Invest in thorough testing and optimization for stability.

Assumption to check: Frequent crashes reported

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

An effect instrument anyone can play - sonic anarchy in the palm of your hand. iOS Mars: "Barely controlled chaos“, "sonic extremes“, "well suited for live use“ Music App Blog: "if you like the occasional dose of sonic mayhem, then this is an app that will let you make it" WretchUp is the sonic instrument from the imagination of Mouse on Mars Instruments. Used by the duo in their live performances, it's a playable effect inspired by analog hardware. Sing into it, speak into it, plug in an instrument, sample sounds, and then make sonic mayhem. It's been tested in Mouse on Mars' live shows and used in studio albums. But now it's available to anyone - whether you're a musician wanting to create unique sounds or you just want to make some wild noises and frighten friends and enemies. // FEATURES - Pitch-shifted delay with feedback and filter - Unique controls, designed to be used in live performance and tested onstage - Play with gestures, even without looking closely at the screen - Record vocals or instruments from the built-in mic or another input - Sample loops and change their speed - Adjust the feedback loop, pitch, and filter for unique sounds - Make inputs by holding down your finger, or lock input for continuous sampling - Inter-App-Audio supported - Audiobus supported www.mouseonmars.com/mominstruments Features artwork by Rupert Smyth. Pure Data-based, open source patch created by Florian Grote and Peter Kirn with Mouse on Mars. App design by Oliver Greschke. Powered by free and open source software libpd. Note: like all mic-based effects, you need to enable microphone input. If you accidentally did not allow mic input, you can allow later via: Device settings, WretchUp, Data settings, Microphone, allow mic input.

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Screenshots

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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.

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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.