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
Date & Time Calculator(Finder)
Find how many days are there for your holiday trip or find weekdays and weekends between two dates.
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.8
32 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.
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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/
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 Date & Time Calculator(Finder): map the core Productivity 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
Include more features like time zone calculations and recurring date ranges.
Assumption to check: Limited functionality for complex date calculations
Validate with people who use this workflow before building.
Hypothesis 2
Add functionality to export results to PDF or share via email.
Assumption to check: No export options for calculations
Validate with people who use this workflow before building.
Hypothesis 3
Enhance UI design and allow users to customize themes.
Assumption to check: Basic UI with little customization
Validate with people who use this workflow before building.
Hypothesis 4
Implement reminders for recurring date calculations.
Assumption to check: No reminders for upcoming calculations
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
Find how many days are there for your holiday trip or find weekdays and weekends between two dates. It will help you to add or subtract Years Months or days to a particular date Which means no need to look at the calendar to figure out 90 days from today. This app has an hour and minutes calculator so that you don't have to convert the time into its decimal parts every time in a regular calculator to figure out your working hours. The weekdays and weekends between two dates is a feature that could come in handy if you have to meet deadlines and figure out how many actual days you could work between those two dates. Find local time in different cities using time zones feature So this app has multiple features that will help you with your calculations with dates, time, years etc. Share what you find with your friends & colleagues using the share button, Easier navigation to switch between features.
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
React Navigation
Date-fns
AsyncStorage
React Native Paper
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.
