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
High Frequency Tones
precisely generate sound waves with high frequency tones and test the limits of what you can hear
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.6
660 ratings · Top 15%
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.
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 High Frequency Tones: map the core Utilities 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
Offer a wider range of frequencies and user-generated tones.
Assumption to check: Limited tone selection compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Provide detailed descriptions and potential uses for each tone.
Assumption to check: No detailed information about tones
Validate with people who use this workflow before building.
Hypothesis 3
Enable users to share their favorite tones with friends.
Assumption to check: Lacks social sharing features
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to customize tone settings, such as duration and fade in/out.
Assumption to check: Limited customization options
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
precisely generate sound waves with high frequency tones and test the limits of what you can hear. did you know that our hearing decays as we grow older? studies show that as we age, we lose our ability to hear up to half of the upper frequency spectrum. now, you can test that concept within a clean and easy-to-use interface. high frequency tones will allow you to generate any frequency up to 20,000 hz – widely considered the upper limit to human hearing. potential uses include: • annoy your friends or classmates without tipping off the teacher or other adults. • use it as a dog whistle or bug deterrent (both of whom have better hearing than humans!). • ward teenagers away from an area. • compete with your friends to determine who has the best hearing! purchase frequency premium for just $0.99 to permanently eliminate ads and choose from four different waveforms.
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
Starter
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.
