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
Costco
It's easy to save time and money while on the go, with the Costco Mobile App! We've improved our mobile app, to make it easier for members to access the incredible values found only at Costco.
Free · In-app purchases
OVERALL US RANK
#73
Free · all categories
REVENUE (Est)
$133K/mo
$74K - $192K
RATING
★ 4.9
1,294,970 ratings · Top 5%
Evidence scope: #73 is the current overall US Free chart position. 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 Costco: map the core Shopping 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 real-time stock updates and notifications for restocks.
Assumption to check: Limited product availability and stock issues
Validate with people who use this workflow before building.
Hypothesis 2
Simplify navigation with clear labeling and intuitive flows.
Assumption to check: In-app navigation can be confusing
Validate with people who use this workflow before building.
Hypothesis 3
Optimize image loading and implement lazy loading for better performance.
Assumption to check: Slow loading times for images and content
Validate with people who use this workflow before building.
Hypothesis 4
Include more payment methods like cryptocurrency and digital wallets.
Assumption to check: Limited payment 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
It's easy to save time and money while on the go, with the Costco Mobile App! We've improved our mobile app, to make it easier for members to access the incredible values found only at Costco. DIGITAL MEMBERSHIP CARD: Access your membership card from the home page of the app. Use your membership card to enter the warehouse and at checkout. SHOP: Browse Costco.com’s unique and expanded selection, which offers thousands of items not found at your local warehouse. Enjoy having items delivered straight to your door! SAVINGS: Conveniently receive the latest Warehouse Savings right on your own device. GAS PRICES: Just tap the locator pin on the map to view current gas prices. PHOTOS: Order metal prints, acrylic prints or photo mugs directly from the app. Have them delivered to your door or pick them up at select Costco locations. SPECIAL EVENTS: View the Special Events happening at your local Costco and set reminders for upcoming events. PHARMACY: Order prescription refills & check status on prescriptions. Get refill reminders, track your medications, manage family accounts, transfer prescriptions, and find a Costco pharmacy. TRAVEL: Shop Costco Travel for great deals on vacation packages, hotels, cruises, rental cars, theme parks and more! BUSINESS CENTER: Stock up on everything from Restaurant Supplies to Office Essentials, and keep your business running smoothly and efficiently. SHOPPING LIST: Keep track of the items you want to pick up on your next trip to Costco. WAREHOUSE INFO: See details about your nearest Costco warehouse, including regular and holiday hours, services provided, driving directions and gas prices. FEEDBACK: Visit our app feedback page and help provide important feedback for Costco, because your opinion matters!
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
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Axios
react-navigation
Shadcn/ui
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.
