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
BASS Hz!
Built for car audio enthusiasts who tune by ear.
$3.99 · In-app purchases
PRICE
$3.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.9
15 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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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included14 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 BASS Hz!: 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 frequency presets and user-defined ranges.
Assumption to check: Limited frequency selection options compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Implement sharing options for users to share their custom frequencies.
Assumption to check: No social sharing features
Validate with people who use this workflow before building.
Hypothesis 3
Include educational content about the significance of different frequencies.
Assumption to check: Lack of detailed frequency information
Validate with people who use this workflow before building.
Hypothesis 4
Clarify pricing and benefits of in-app purchases during onboarding.
Assumption to check: In-app purchase confusion
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
Built for car audio enthusiasts who tune by ear. Test subs, amps, and enclosures with precise bass tones from 10–150 Hz, in the driveway, garage, or at home. Dial in your sub. Find rattles. Set your gain right. Generate clean bass tones from 10–150 Hz to test and tune car or home audio while using pure frequencies, not music. Built on Apple’s Core Audio engine for accurate, low-distortion tone generation. Perfect for: • Finding and fixing rattles and buzzes in your vehicle • Setting amplifier gain and boost with precision • Stress-testing subwoofers to find their best response • Prepping and fine-tuning systems for audio competitions Features: • Bass tones from 10 Hz to 150 Hz • Real-time frequency adjustment as you listen • Five preset bass tracks included • Noise Test mode • Sweep Test mode (20 Hz–20,000 Hz) • Fine-grained control for precise tuning IMPORTANT — READ BEFORE USE This app generates very low bass frequencies not typically found in music. Always start at low volume. Unmonitored use at high volume can damage speakers, subwoofers, and amplifiers. Know your system’s limits and monitor volume at all times.
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.
SUGGESTED BUILD STACK
React Native
Expo
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react-native-slider
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.
