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
MarginKeeper: Margin & Tariff
Skip the spreadsheet
$4.99
PRICE
$4.99
No 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.
Build your own version
Build Kit
Make this idea yours
A product spec, screen plans, and build steps for your coding agent.
First kit free with a verified email
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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 included
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.
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App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Screenshots
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App Store description
Skip the spreadsheet. Run the numbers. Cost changed? Customer wants a better price? Tariff went up? MarginKeeper is a pricing calculator built for the moment you need the answer, not when you're back at your desk. FOUR TOOLS. ONE TAP. Find Sell Price Enter your cost and target margin. MarginKeeper gives you the sell price and the profit behind it. Then use the slider to try a higher or lower price and watch your margin and profit update. Find Margin Already have a price? Enter your cost and sell price to see the margin you're really making and the profit per unit. Find Discount Putting something on sale? Enter the original price and the sale price to see the discount percentage and the amount off. Include Tariff A tariff changed your cost. Enter your product cost, tariff and margin, then choose: • Keep Profit: hold your profit per unit steady and see how much margin you give up. • Keep Margin: protect your margin percentage and see the new sell price and profit. See the price, profit and margin before and after the tariff, and exactly how much each one changed. MARGIN, NOT MARKUP MarginKeeper calculates true margin: profit as a percentage of the sell price. A product that costs 10.50 and sells for 42.00 has a 75% margin, not a 300% one. ONE APP. EVERY CURRENCY. No currency settings. No conversions. Just enter your numbers. MarginKeeper uses plain numbers, so it works with whatever currency your business uses. BUILT FOR • Sales teams quoting on the spot • Business owners setting prices • Importers and exporters dealing with tariffs and duties • Resellers, wholesalers and makers pricing their products YOUR NUMBERS STAY WITH YOU No account. No ads. No tracking. MarginKeeper doesn't collect any data. One-time purchase. No subscription. Questions or feedback: [email protected]
Written user reviews are not shown here. Check current App Store reviews >
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.
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
BUILD KIT DIFFICULTY
Not assessed in a Build Kit yet.
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.
