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
PCGS CoinFacts Coin Collecting
Coin collectors finally have the resource needed to make informed numismatic buying, selling and trading decisions, thanks to the PCGS CoinFacts mobile app
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.8
66,594 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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Combine features and design from your favorite apps.
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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 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 PCGS CoinFacts Coin Collecting: map the core Reference 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
Implement advanced filtering and sorting options for accurate results.
Assumption to check: Limited search functionality, results can be inaccurate.
Validate with people who use this workflow before building.
Hypothesis 2
Offer a clear comparison of features between free and premium versions.
Assumption to check: In-app purchases can be confusing and lack clear value.
Validate with people who use this workflow before building.
Hypothesis 3
Design a cleaner, more organized layout with better use of whitespace.
Assumption to check: The UI can feel cluttered with too much information.
Validate with people who use this workflow before building.
Hypothesis 4
Incorporate a detailed onboarding tutorial for first-time users.
Assumption to check: User onboarding is minimal, making it hard for new 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
Coin collectors finally have the resource needed to make informed numismatic buying, selling and trading decisions, thanks to the PCGS CoinFacts mobile app. The world’s largest encyclopedia of U.S. coins now fits in your pocket and is 100% free to use. Download this coin collecting mobile app today to access coin values, coin populations, images, narratives, auction prices realized, and more for over 40,000 U.S. coins. Features include: * Barcode scanning for coins graded by PCGS and NGC provides instant coin look-up functionality * Full PCGS Price Guide listings for all U.S. Coins * Full PCGS population Report for all U.S. Coins * Access PCGS Photograde with high resolution images by grade * Millions of auction prices realized from PCGS & NGC graded coins, pulled from over 5,800 auctions, including Heritage, eBay, Sotheby’s, Christie’s, Bonham’s, Stack’s Bowers, Legend Rare Coin Auctions and others * Complete numismatic specifications for all U.S. coin types * Expert narratives on specific coins from leading industry professionals like David Hall, Ron Guth, Q. David Bowers and others * Coin rarity and survival estimates by grade * Coin condition census listings * High resolution photography * Detailed coin variety attribution with photographs The PCGS CoinFacts application requires an active internet connection to operate. * See the Collectors Universe (parent company of PCGS) Privacy Policy and Terms of Use: http://www.collectorsuniverse.com/privacy ** If you were previously a paid PCGS CoinFacts subscriber through the App Store, you may check on and/or cancel your subscription here: https://buy.itunes.apple.com/WebObjects/MZFinance.woa/wa/manageSubscriptions
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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-reanimated
expo-router
BUILD KIT DIFFICULTY
Advanced
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.
