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
Tip — Gratuity Calculator
Whether you're splitting the check after a night out or tipping the pizza delivery guy, Tip makes it fast, easy, and drama-free — right from your iPhone or Apple Watch
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.6
9 ratings · Top 15%
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 should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
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 Tip — Gratuity Calculator: map the core Food & Drink 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
Offer customizable settings for rounding tips or adding service fees.
Assumption to check: Limited customization options for tip calculation.
Validate with people who use this workflow before building.
Hypothesis 2
Implement a history feature to track past calculations.
Assumption to check: No ability to save tip history.
Validate with people who use this workflow before building.
Hypothesis 3
Provide clear explanations for what features are locked behind the paywall.
Assumption to check: In-app purchases may confuse users.
Validate with people who use this workflow before building.
Hypothesis 4
Add multiple themes and visual styles to enhance user experience.
Assumption to check: Lack of visual appeal and themes.
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
Whether you're splitting the check after a night out or tipping the pizza delivery guy, Tip makes it fast, easy, and drama-free — right from your iPhone or Apple Watch. Just point your camera at the bill and Tip does the rest. No typing, no squinting at the receipt — just instant results so you can get back to the fun. Stop doing math in your head. Start enjoying the moment. No ads. Just good vibes and great tips. What's on the menu: • Snap a photo of your bill to get started instantly • Bill amount is all you need if you prefer to type • 4 customizable tip presets to match your style • Split with up to 50 friends and send via iMessage • Quick action shortcuts for when you're in a hurry • Rounding so the math always works out • Dark mode for those late-night dinners • Full Apple Watch app — tip right from your wrist • Apple Watch complications for instant access
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
Async Storage
Styled Components
React Native Slider
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.
