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
Instant Compound Calc!
A simple yet powerful compound interest calculator that computes complex calculations instantly!
$2.99
PRICE
$2.99
No in-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
N/A
No ratings yet
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 Instant Compound Calc!: map the core Finance 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 features to include graphs and comparison tools
Assumption to check: Limited functionality for advanced financial calculations
Validate with people who use this workflow before building.
Hypothesis 2
Implement user login and save calculation history
Assumption to check: No user account or history management
Validate with people who use this workflow before building.
Hypothesis 3
Add a help section with examples and tutorials
Assumption to check: Lack of detailed help or tutorials
Validate with people who use this workflow before building.
Hypothesis 4
Integrate options for recurring deposits or withdrawals
Assumption to check: No recurring calculation features
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
A simple yet powerful compound interest calculator that computes complex calculations instantly! With easy operation, it displays highly accurate results. ＜App Features＞ 1. Simple and intuitive UI: Just input principal, annual rate, and years elapsed for easy compound interest calculation. The visually clear design ensures even first-time users can use it confidently. 2. Lightning-fast calculation: Tap the "Calculate" button after input to instantly view results. See the power of compound interest right away. 3. Clear results display: Results appear in large, easy-to-read fonts. Check principal plus interest and interest amounts for each year in detail. 4. User-friendly input keyboard: Optimized numeric keyboard with easy close button for smooth input. 5. Error prevention: Detects invalid inputs and shows error messages. Ensures accurate calculations with peace of mind. ＜Recommended For＞ * Investors (beginner to advanced): Simulate investment growth for future planning * Household managers: Understand savings and investment effects concretely * Educators: Use as a financial education tool for students * Economics learners: Learn compound interest concepts hands-on ＜Compound Interest Formula＞ * Total Amount = Principal × (1 + Annual Rate/100) ^ Years Elapsed Simple operation for precise compound interest calculations, anytime anywhere. Your essential tool for asset building! Paid app with no ads whatsoever.
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
@react-navigation/native
@react-native-async-storage/async-storage
react-native-paper
TypeScript
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.
