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
Exchange Rates & Converter
Exchange Rates is a user-friendly app for checking real-time exchange rates and converting currencies
$5.99 · In-app purchases
PRICE
$5.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.9
8 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.
Build your own version
Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
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/
Preview a sample Build Kit No email needed
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 Exchange Rates & Converter: map the core Travel 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
Include more currencies and user customization for favorites.
Assumption to check: Limited currency options compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Provide clear descriptions and benefits for premium features.
Assumption to check: In-app purchases are unclear and not well-communicated
Validate with people who use this workflow before building.
Hypothesis 3
Allow users to access recent conversions without internet.
Assumption to check: Lacks offline functionality
Validate with people who use this workflow before building.
Hypothesis 4
Introduce graphical representations of historical exchange rates.
Assumption to check: No historical data analysis for 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
Exchange Rates is a user-friendly app for checking real-time exchange rates and converting currencies. It works offline and supports over 150 global currencies, including cryptocurrencies. You can track both market exchange rates and P2P rates. Switching from viewing rates to the converter takes just one click. The app allows you to convert multiple currencies at once, and the built-in calculator makes the process even more convenient. If you’re traveling, the app will automatically suggest adding the local currency, ensuring you always have up-to-date exchange rate information. This feature is especially helpful for tourists and business travelers. Customizable widgets let you select your preferred currencies and monitor their rates directly from your home screen or lock screen (iOS 16+), without needing to open the app.
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
Axios
Zustand
react-navigation
expo-sqlite
BUILD KIT DIFFICULTY
Intermediate
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.
