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
JarBox
Remember when the best games fit in your pocket — on a phone with actual buttons? JarBox brings that era back to your iPhone.
$1.99 · In-app purchases
PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
N/A
No ratings yet
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 included16 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 JarBox: map the core Entertainment 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 recommendation algorithms and personalized suggestions.
Assumption to check: Limited content discovery features compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Include offline downloads for premium users.
Assumption to check: Lack of offline access to content
Validate with people who use this workflow before building.
Hypothesis 3
Introduce customizable parental control settings.
Assumption to check: No parental controls available
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to share content on social media platforms.
Assumption to check: Missing social sharing features
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
Remember when the best games fit in your pocket — on a phone with actual buttons? JarBox brings that era back to your iPhone. JarBox is a J2ME (Java ME) emulator that runs the MIDP 2.0 / CLDC 1.1 games and apps you grew up with. Just drop in a .jar file and play — no fuss, no setup. Features: - Run real J2ME games — load classic .jar titles straight from the Files app - Full 3D support — hardware-accelerated MascotCapsule micro3D and M3G, so the 3D classics look the way you remember them - Faithful 2D rendering — Canvas, Sprites, TiledLayers — pixel-perfect - Sound & music — WAV, MP3, MIDI playback and ToneControl - Wide compatibility — Nokia, Siemens, Samsung, Motorola, Sony Ericsson and other vendor extensions supported Dust off the classics. Whether it's a racing game from a Nokia, a 3D action title, or that one puzzle you could never put down — JarBox runs it. Got an old favorite in mind? Load it up and play.
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-image
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.
