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
PepProCalc: Peptide Calculator
PepProCalc makes peptide math effortless.
$6.99 · In-app purchases
PRICE
$6.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.8
25 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 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 PepProCalc: Peptide Calculator: map the core Health & Fitness 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
Allow users to input custom concentrations and save them.
Assumption to check: Limited customization of peptide concentrations
Validate with people who use this workflow before building.
Hypothesis 2
Add an option to export calculation history as CSV or PDF.
Assumption to check: No export feature for history
Validate with people who use this workflow before building.
Hypothesis 3
Include an onboarding tutorial to help users understand how to use the app.
Assumption to check: Lack of tutorial or guidance for new users
Validate with people who use this workflow before building.
Hypothesis 4
Provide more complex calculation options for experienced users.
Assumption to check: Few advanced calculation 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
PepProCalc makes peptide math effortless. Designed with a clean, distraction free interface, it calculates your draw amount instantly based on vial size, water volume, and desired dose. No clutter. No confusion — just precision. Features • Accurate dosing calculator – instantly see how many units to draw for any peptide or dose. • Smart presets – includes popular compounds like Semaglutide, Tirzepatide, Retatrutide, CJC-1295, Ipamorelin, and BPC-157. • Custom mode – enter any vial configuration and get exact results. • Quick-save history – revisit previous calculations anytime. • Dark, minimalist design – focused on clarity, readability, and speed. • One-tap share – send dosing information instantly. Built for professionals, health enthusiasts, and anyone who values accuracy and simplicity, PepProCalc brings modern design and precision to peptide dosing. This app is intended for educational and informational purposes only. It does not provide medical advice, diagnosis, or treatment, and should not replace consultation with a qualified healthcare provider.
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
AsyncStorage
React Native Paper
React Native Picker Select
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.
