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
Schengen Days Calculator
Travel Europe with Confidence
$2.99 · In-app purchases
PRICE
$2.99
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 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 Schengen Days Calculator: map the core Travel 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
Provide detailed explanations and examples of Schengen rules.
Assumption to check: Users often struggle with complex visa rules and calculations.
Validate with people who use this workflow before building.
Hypothesis 2
Implement clear date pickers with visual cues.
Assumption to check: Date input can be confusing and imprecise.
Validate with people who use this workflow before building.
Hypothesis 3
Introduce a comprehensive history feature that saves all previous calculations.
Assumption to check: Lack of history management can lead to data loss.
Validate with people who use this workflow before building.
Hypothesis 4
Include a tutorial or tips section explaining calculations in detail.
Assumption to check: Users may not understand remaining days calculation.
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
Travel Europe with Confidence. Your Schengen Visa Companion. Navigate your European journey with total peace of mind. Schengen Days is the ultimate tool for anyone who travels within the Schengen Area, providing instant, accurate calculations for the 90/180-day rule. Ditch the manual spreadsheets and travel without the worry of overstaying. Key Features: - Effortless Tracking: Log trips in seconds and watch your available days update automatically. Know your exact stay duration at a glance. - Smart Overstay Alerts: Our proactive alerts notify you before you hit your limit, so you're always in control and fully compliant. - Seamless Sync: Your travel history is securely stored and synced across all your Apple devices via iCloud. - Advanced Features: Easily mark trips with special exemptions or visas. Our app is built with the official EU Commission rules in mind, but we make it easier. Schengen Days gives you the power to manage your travel history effortlessly, so you can focus on the adventure. Travel Smarter. Stay Longer. Download Schengen Days today and unlock your next European journey!
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
Supabase
React Query
Day.js
React Navigation
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.
