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.
App Overview
432 & 528 Tuner
Introducing the 432 Tuner, an app designed to assist you in tuning your musical instrument to the A=432hz tuning, as well as A=444Hz (C5=528Hz) and the Standard 440Hz
$5.99 · In-app purchases
PRICE
$5.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 3.5
84 ratings · Top 50%
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 included17 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.
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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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for 432 & 528 Tuner: 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
Add more frequencies and custom tuning options.
Assumption to check: Limited tuning options beyond 432 Hz and 528 Hz
Validate with people who use this workflow before building.
Hypothesis 2
Implement a clearer onboarding process and tutorials.
Assumption to check: User interface can be confusing for new users
Validate with people who use this workflow before building.
Hypothesis 3
Allow users to share their tuning sessions on social media.
Assumption to check: No social features or sharing capabilities
Validate with people who use this workflow before building.
Hypothesis 4
Offer a free trial for premium features to increase user acquisition.
Assumption to check: In-app purchases may deter users
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
Introducing the 432 Tuner, an app designed to assist you in tuning your musical instrument to the A=432hz tuning, as well as A=444Hz (C5=528Hz) and the Standard 440Hz. With this tool, tuning to A=432hz has never been easier. The 432 Tuner also offers the ability to tune to A=444hz, which uses the 528hz scale, as well as the Standard A=440hz. Although our initial goal was to keep our inventions free of charge, we have come to the realization that we need to sustain ourselves while continuing to develop new and existing projects. All of our creations are made from the heart, with a focus on Love, Light, and Meditation.
Written user reviews are not shown here. Check current App Store reviews >
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.
