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
Metric Conversions Premium
Premium version of the unit converter app from the most popular metric conversions website in the world, metric-conversions.org
$4.99 · In-app purchases
PRICE
$4.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
1 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 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 Metric Conversions Premium: 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
Expand unit categories and add more conversion options.
Assumption to check: Limited unit options compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Implement a favorites feature for quick access.
Assumption to check: No way to save favorite conversions
Validate with people who use this workflow before building.
Hypothesis 3
Redesign the UI for a more modern look.
Assumption to check: User interface can feel outdated
Validate with people who use this workflow before building.
Hypothesis 4
Add themes and layout preferences.
Assumption to check: Lack of user 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
Premium version of the unit converter app from the most popular metric conversions website in the world, metric-conversions.org. Over a billion visitors have used our website, try our app and see why we're so popular! FEATURES: No advertisements, tracking or any of your user data used Easy to use clear interface Works offline All popular unit conversions (over 30,000 of them) Over 130 currencies (including Bitcoin) with exchange rates updated every hour Store your favorite conversions for quick access Answers in fractions where needed. Obtain conversion results with up to 5 decimal places Imperial units split into other imperial units – so you can get a weight in stones and pounds, pounds and ounces, etc. Lengths break down into feet and inches, etc. WEIGHT: Kilograms, Pounds, Stones, Ounces, Grams, Carats, Grains, Hundredweights, Microgram, Milligrams, Ounces, Pennyweights, Tons, Troy pounds, Troy ounces TEMPERATURE: Celsius, Fahrenheit, Kelvin, Rankine, Newton, Réaumur, Rømer, Delisle. LENGTH: Miles, Yards, Feet, Inches, Kilometers, Meters, Centimeters, Chains, Decimeters, Furlongs, Leagues, Lightyears, Microinches, Microns, Millimeters, Parsecs, Nautical Leagues, Nautical Miles. AREA: Square Miles, Acres, Square Yards, Square Feet, Square Inches, Square Kilometers, Hectares, Square Meters, Square Centimeters, Square Millimeters, Square Microns, Square Microinches. VOLUME: Cups, Tablespoons, Teaspoons, Gallons, Pints, Gills, Ounces , Cubic Meters, Liters, Centiliters, Milliliters, Cubic Yards, Barrels, Quarts, Gills. SPEED: Miles per hour, Kilometers per hour, Meters per second, Knots, Mach, Light speed and more. TIME: Seconds, Minutes, Hours, Days. ANGLE: Degrees, Radians, Minutes (Angular), Seconds (Angular), Centrad, Gradians, Milliradians, Sign PRESSURE: Atmospheres, Bar, Pascals, Pound Force per Square Inch, Inches of Mercury, Inches of Water, Kilogram Force per Square Meter, Millibar, Millimeters of Mercury, Millimeters of Water, Newtons per Meter Squared, Pounds per Square Foot, Torrs CURRENCY: All state sponsored world currencies as well as Bitcoin. If you need anything added, email us at [email protected] and we'll do our best to put them in for you!
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
React Native Picker
Async Storage
Expo Clipboard
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.
