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
Financial Calculator Plus
This app integrates multiple functions such as finance, loans, retirement planning and scientific calculations to provide users with comprehensive financial planning and calculation tools
$4.99 · In-app purchases
PRICE
$4.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
6 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 Financial Calculator Plus: 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
Include more specialized calculators like Retirement or Tax calculators.
Assumption to check: Limited calculator options compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Implement a more intuitive navigation system with quick access to favorites.
Assumption to check: Difficult to navigate between different calculators
Validate with people who use this workflow before building.
Hypothesis 3
Add charts/graphs to visualize calculations and trends.
Assumption to check: Lack of visual data representation
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to perform calculations offline and sync when connected.
Assumption to check: No offline functionality
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
This app integrates multiple functions such as finance, loans, retirement planning and scientific calculations to provide users with comprehensive financial planning and calculation tools. The ultimate solution to meet all your calculation and financial needs. Basic calculation functions Standard math operations Percentage calculations Memory functions Clear and undo operations Financial calculation functions ROI (return on investment) calculations Compound interest calculations IRR (internal rate of return) calculations MIRR (modified internal rate of return) calculations TVM (time value of money) calculations Bond calculations Foreign exchange calculations Tax equivalent return calculations Rule of 72 calculations Loan calculation functions Basic loan calculations Loan comparisons Refinancing analysis APR calculations Commercial loans Loan analysis Housing affordability assessments Renting vs. buying comparisons Biweekly payment analysis Interest-only loan calculations Rental property analysis Retirement planning functions Features Basic retirement calculations Detailed retirement planning Pension calculations Social security calculations Retirement withdrawal strategies Portfolio planning Inflation analysis Medical expense planning Estate planning Scientific calculations Mathematical operations (square, square root, etc.) Trigonometric calculations Logarithmic operations Statistical calculations Base conversion Scientific constants Unit conversion Featured functions Clear user interface Real-time calculation results Detailed analysis reports Graph visualization Comparison of multiple calculation solutions Professional suggestions and tips Applicable groups Personal financial management users Financial practitioners Investment and financial advisors Real estate agents Retirement planners Students and educators
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
TypeScript
react-native-reanimated
react-native-gesture-handler
BUILD KIT DIFFICULTY
Intermediate
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.
