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
MaraTapeCal
MaraTapeCal makes calibrating an analog tape machine fast and easy
$24.99 · In-app purchases
PRICE
$24.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.0
8 ratings · Top 30%
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/
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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 MaraTapeCal: map the core Reference 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
Expand the range of units and conversions available.
Assumption to check: Limited unit options compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Implement user accounts to save conversion history.
Assumption to check: No user account or history feature
Validate with people who use this workflow before building.
Hypothesis 3
Offer a more competitive pricing model or additional features.
Assumption to check: High price point for a simple calculator
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to customize their interface and settings.
Assumption to check: Lack of 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
MaraTapeCal makes calibrating an analog tape machine fast and easy. Learn how to calibrate an analog tape machine just like the Mara Machines technicians do! Offered by Mara Machines (the authority on MCI tape machine restoration) MaraTapeCal is a step by step guide to calibrating analog tape machines of all types. Simply answer questions about tape formulation, tape speed and MRL reference level, then the app automatically calculates bias level and elevation level taking out the guesswork or confusing charts. In app purchases include ‘personal shopper’ links to the same equipment Mara Machine technicians use. You’ll be a pro in no time with MaraTapeCal! -step by step guide made for beginners and seasoned pros alike -photos of actual tape machines that highlight which buttons to push -photos of actual tape machines that highlight which pot to adjust -in depth alignment technique that will allow your tape machine to sound it’s best -quick alignment ‘touch up’ option between full calibrations - Personal Shopper available via in-app purchase to help you quickly source calibration tools if you need help finding them
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.
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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.
