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
ProCalc.app: Margin, BreakEven
ProCalc.app brings professional business calculators into one fast, focused app: margin rate, break-even point, fees/commissions and Mini Business Plan.
$3.99 · In-app purchases
PRICE
$3.99
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 included15 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 ProCalc.app: Margin, BreakEven: 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 advanced financial calculators like ROI, NPV.
Assumption to check: Limited calculations and features compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Implement share functionality for results via social media or email.
Assumption to check: No sharing options for results
Validate with people who use this workflow before building.
Hypothesis 3
Introduce user accounts with saved calculations.
Assumption to check: No user account management
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to customize themes and layouts.
Assumption to check: No customization options
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
ProCalc.app brings professional business calculators into one fast, focused app: margin rate, break-even point, fees/commissions and Mini Business Plan. Price products, services and offers with a clearer view of costs, VAT/sales tax, discounts, payment fees, marketplace commissions, freelance platform fees, margins and profitability. Whether you sell online, run a shop, freelance, consult or test a new offer, ProCalc.app helps you answer the question that matters: is this price actually profitable? ■ MINI BUSINESS PLAN Turn saved calculations into a monthly profitability snapshot. Import a fee, margin or break-even scenario, add expected monthly sales and a profit target, then get a clear summary: monthly revenue, cost of goods, total fees, profit, break-even sales, required price and gap to target. ■ SAVED SCENARIOS AND COMPARISONS Save a calculation for a product, client, offer or sales channel. Compare two scenarios side by side, see which one wins on the key metric, and update a loaded scenario after changes instead of creating duplicates. ■ CHARTS AND EXPORTS Visualize costs, margins, fees, fixed costs and profit with simple business charts. Export a clean PDF report and CSV file to share with a partner, accountant, client or team. ■ MARGIN CALCULATOR Enter purchase cost, target margin, markup, coefficient, sale price, tax or discount. ProCalc.app instantly calculates sale prices before/after tax, discounted price, margin rate, markup rate and coefficient. ■ BREAK-EVEN CALCULATOR Estimate when an activity becomes profitable. Add units sold, sale price, variable costs, fixed costs and period to calculate break-even value, break-even units, result and time to profitability. ■ FEES, MARKETPLACES AND FREELANCE Know your real profit after fees. Calculate payment fees, shipping, taxes, platform commissions and profit after costs. Use adjustable templates for PayPal, Stripe, Amazon, Etsy, eBay, Shopify, WooCommerce, Square, SumUp, Mercado Pago, Klarna, TikTok Shop, ComeUp, Fiverr, Malt, Upwork and more. ■ TARGET DIAGNOSTICS A margin number is useful; knowing whether it is healthy is better. ProCalc.app highlights whether a scenario is healthy, needs attention or is risky based on your target. ProCalc.app is built for entrepreneurs, shop owners, freelancers, makers, consultants and small teams who need professional pricing decisions without rebuilding spreadsheets. Download ProCalc.app and make better pricing decisions in seconds.
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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
Zustand
React Navigation
React Native Paper
TypeScript
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.
