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
ABV Calculator: Brew & Distill
Calculate ABV, correct hydrometer readings, convert SG, Brix, Plato and Proof, and dilute spirits to a target strength in one focused tool for brewers and distillers.
$4.99 · In-app purchases
PRICE
$4.99
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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Combine features and design from your favorite apps.
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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 ABV Calculator: Brew & Distill: 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
Add features like saving calculations or sharing results.
Assumption to check: Limited functionality beyond basic calculations
Validate with people who use this workflow before building.
Hypothesis 2
Enable users to save favorite calculations for quick access.
Assumption to check: Lack of user personalization
Validate with people who use this workflow before building.
Hypothesis 3
Integrate social media sharing for results.
Assumption to check: No social sharing options
Validate with people who use this workflow before building.
Hypothesis 4
Introduce a subscription model for premium features.
Assumption to check: Single purchase model can limit user access
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
Calculate ABV, correct hydrometer readings, convert SG, Brix, Plato and Proof, and dilute spirits to a target strength in one focused tool for brewers and distillers. Built for real brew-day and distilling work: - Metric, US Customary, and Imperial unit switching (Liters, Gallons, Kilograms, Pounds) support - Alcohol temperature correction based on standard density tables - Hydrometer ABV calculation from original and final gravity - Refractometer tools for Brix correction and ABV estimation - SG, Brix, Plato, Proof and ABV conversion in one place - Alcohol dilution with volume contraction considered - Local history to review recent calculations - Celsius and Fahrenheit display support Why it converts better than generic calculators: - Faster input flow with dedicated tools instead of one overloaded form - Practical units used in brewing and distilling - Offline-first workflow for cellar, brew room and workshop use - Clear results with less noise and no irrelevant tracking features Use it for homebrew batches, fermentation checks, spirit dilution, and day-to-day measurement conversions when accuracy and speed matter.
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
react-native-paper
@react-native-async-storage/async-storage
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.
