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
Napkin Real Estate Calculator
ANALYZE REAL ESTATE DEALS IN UNDER 60 SECONDS
$49.99 · In-app purchases
PRICE
$49.99
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 Napkin Real Estate Calculator: map the core Business 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
Add more diverse calculators for various real estate scenarios
Assumption to check: Limited calculator options compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Implement user feedback mechanisms to improve app features
Assumption to check: Lack of user feedback and reviews
Validate with people who use this workflow before building.
Hypothesis 3
Offer a free trial period to attract more users
Assumption to check: High upfront cost without trial
Validate with people who use this workflow before building.
Hypothesis 4
Incorporate community features like sharing calculations or tips
Assumption to check: Minimal user engagement 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
ANALYZE REAL ESTATE DEALS IN UNDER 60 SECONDS Napkin Underwriting is a powerful real estate deal analyzer designed for multifamily investors, apartment buyers, and real estate professionals who need to evaluate deals fast. Instead of spending hours building spreadsheets, this app lets you quickly analyze a real estate investment and determine whether a deal is worth pursuing. Enter a few numbers and instantly calculate the most important metrics used by professional investors. Perfect for quick napkin underwriting when reviewing deals on the go. KEY INVESTMENT METRICS CALCULATED Napkin Underwriting instantly calculates: • Net Operating Income (NOI) • Cap Rate (%) • Cash Flow After Debt • Debt Service • Debt Coverage Ratio (DSCR) • Effective Gross Income • Price Per Unit • Market Cap Rate • Fair Market Value (FMV) • Total Acquisition Cost These calculations help you quickly understand the profitability and potential of a real estate investment. BUILT FOR MULTIFAMILY REAL ESTATE INVESTORS Napkin Underwriting is designed specifically for professionals analyzing: • Multifamily properties • Apartment buildings • Rental property investments • Commercial real estate deals The app helps you screen deals instantly before running a full underwriting model. WHY INVESTORS USE NAPKIN UNDERWRITING • Analyze deals in under 60 seconds • Simple and intuitive real estate calculator • Instantly calculate cap rate and NOI • Quickly evaluate multifamily investment opportunities • Avoid complex spreadsheets • Run deal analysis anywhere Professional investors review hundreds of deals before buying one. Napkin Underwriting helps you quickly decide which deals deserve deeper analysis. MAKE SMARTER INVESTMENT DECISIONS Before building a full underwriting model, use Napkin Underwriting to answer the most important question: Is this deal worth your time? Download Napkin Underwriting today and analyze your next real estate investment in seconds.
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-navigation/native
react-native-paper
react-native-async-storage
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.
