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
EXTOOLS®mobile
In ExTools you find the following 21 functions:
$12.99 · In-app purchases
PRICE
$12.99
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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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/
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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 EXTOOLS®mobile: 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
Provide in-depth tutorials and video guides for each tool.
Assumption to check: Limited tool descriptions and usage examples
Validate with people who use this workflow before building.
Hypothesis 2
Offer a freemium model with basic tools available for free.
Assumption to check: High price point for access
Validate with people who use this workflow before building.
Hypothesis 3
Implement user ratings and reviews for tools to build community trust.
Assumption to check: Poor user feedback and rating
Validate with people who use this workflow before building.
Hypothesis 4
Introduce user profiles and preferences for a tailored experience.
Assumption to check: Lack of personalization features
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
In ExTools you find the following 21 functions: Ignitability Indices 1.minimal ignition energy: influence of temperature 2.minimal ignition energy: influence of median value 3.minimal ignition energy: influence of gas 4.minimal ignition temperature: conversion GG to BAM / BAM to GG 5.Ignition hazard of sparks 6.Equivalent energy of cone discharges 7.Adiabatic compression ignition Explosion Indices 8.Lower explosion level : influence of temperature 9.Pmax: influence of temperature 10.Pmax: influnece of initial pressure 11.Kmax : influence of initial pressure 12.LOC : influence of temperature 13.LOC : conv. N2. - CO2 14.LOC : estimation with MIE and MIT Equipment 15.Rotary air lock 16.Maximum experimental safe gap (MESG) 17.Flexible Intermediate bulk container (FIBC) 18.Circumferential speed and ignition hazard 19.Safe diameter to avoid cone discharges 20.Calculation of Froude-Number Frw 21.Permissible filter fabrics for dust collectors don’t be old-fashioned ... get your ExTools for a most innovative and effective work in explosion safety!
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
Zustand
Supabase
React Navigation
BUILD KIT DIFFICULTY
Intermediate
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.
