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
Numpad 2
Numpad – A Better Way to Enter Numbers
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.5
20 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 included17 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 Numpad 2: 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
Introduce advanced calculation features like graphing or history analysis.
Assumption to check: Limited functionality compared to full calculator apps
Validate with people who use this workflow before building.
Hypothesis 2
Implement a responsive design that adapts to different screen sizes.
Assumption to check: Cluttered UI on smaller devices
Validate with people who use this workflow before building.
Hypothesis 3
Allow users to customize button layouts and themes.
Assumption to check: No user customization options
Validate with people who use this workflow before building.
Hypothesis 4
Enhance sharing features to include direct messaging and social media integration.
Assumption to check: Difficult to share results directly
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
Numpad – A Better Way to Enter Numbers When all you need is numbers, the default keyboard just gets in the way. Numpad gives you a clean, focused, and efficient typing experience—designed for speed and precision. Whether you’re entering prices, codes, or data, Numpad keeps things simple and fast. — Designed for how you work: • Adaptive action key Quickly switch between decimal, space, tab, and more – just press and hold. • Two intuitive layouts Choose between classic 1–9 or calculator-style 7–8–9. Switch instantly by holding the “5” key. • Flexible height Adjust the keyboard to match your preference – compact or spacious – with a simple hold on “0”. • Minimal by design No distractions. No unnecessary keys. Just a better way to enter numbers. — Have an idea or feature request? I’d love to hear from you – your feedback helps shape future updates.
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
Zustand
react-navigation
expo-sharing
react-native-clipboard
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.
