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
Endo Calc
Endo Calc is an app developed for the practicing endocrinologist by an endocrinologist
$3.99 · In-app purchases
PRICE
$3.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
11 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 included13 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 Endo Calc: map the core Utilities 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 detailed logs and reminders for symptoms.
Assumption to check: Limited features for advanced symptom tracking
Validate with people who use this workflow before building.
Hypothesis 2
Implement iCloud sync for data persistence.
Assumption to check: No iCloud sync functionality
Validate with people who use this workflow before building.
Hypothesis 3
Integrate a community feature for user discussions and tips.
Assumption to check: Lack of community support or resources
Validate with people who use this workflow before building.
Hypothesis 4
Provide clearer explanations of premium features and trials.
Assumption to check: In-app purchasing model can be confusing
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
Endo Calc is an app developed for the practicing endocrinologist by an endocrinologist. Many routine tasks that require complex calculations can be done using Endo Tools in a few clicks! Features include: 1) Convert HbA1c to average blood glucose and fructosamine. 2) Convert steroids. 3) Thyroid nodule volume calculator 4) Thyroid cancer staging 5) Thyroxine dose calculator 6) Calcium corrected for albumin 7) Fractional excretion of calcium for familial benign hypocalcuric hypercalcemia 8) NAFLD fibrosis score and several other calculators. The information on this App is not a substitute for professional medical advice, diagnosis, or treatment. All content, including text, graphics, images, and information, contained on or available through this App is for general information purposes only. This app is intended for educational purposes only and is not intended to diagnose, treat or cure any disease based on the sole output of the app. Seek a doctor’s advice in addition to using this app and before making any medical decisions.
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.
