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
Chemical Engineering Formulate
CHEMICAL ENGINEER is the essential tool for Chemical Engineers, Process
$4.99 · In-app purchases
PRICE
$4.99
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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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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Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Chemical Engineering Formulate: map the core Productivity 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 database and provide user contributions
Assumption to check: Limited formula database compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Simplify the navigation and enhance the UI for better user experience
Assumption to check: User interface can be overwhelming
Validate with people who use this workflow before building.
Hypothesis 3
Implement a favorites section for users to save frequently used formulas
Assumption to check: Lack of advanced features like saving favorites
Validate with people who use this workflow before building.
Hypothesis 4
Add offline capabilities to access formulas without internet connection
Assumption to check: No offline access to formulas
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
CHEMICAL ENGINEER is the essential tool for Chemical Engineers, Process Engineers, and engineering students. With over 1,500 formulas and calculators, this is the most comprehensive chemical engineering reference app available. The app features 700+ engineering calculators across 50 categories, 750 conversion formulas, 8 temperature scales, and 14 reference tables. All formulas support US and Metric (SI) units with one-tap toggle and dual-unit display. CORE CHEMICAL ENGINEERING - Heat Transfer -- LMTD, overall heat transfer, fin efficiency, radiation, Fourier's law - Fluid Mechanics -- Reynolds number, Bernoulli, Darcy-Weisbach, Hagen-Poiseuille - Thermodynamics -- Ideal gas, Clausius-Clapeyron, Antoine equation, compressibility - Reaction Kinetics -- Arrhenius equation, rate laws, CSTR/PFR design, Levenspiel - Mass Transfer -- Fick's law, mass transfer coefficients, wetted wall columns - Distillation -- McCabe-Thiele, Fenske, Underwood, relative volatility - Dimensionless Numbers -- Reynolds, Nusselt, Prandtl, Schmidt, Sherwood, Grashof UNIT OPERATIONS Filtration, Packed/Fluidized Beds, Compressor Sizing, Mixing, Cooling Towers, Membrane Separation, Crystallization, Liquid-Liquid Extraction, Adsorption PROCESS & SAFETY Process Economics, Process Control, Safety Engineering, Corrosion and Electrochemistry ENVIRONMENTAL Air Quality, River/Lake/Soil Pollution, Infiltration and Recharge, Evaporation, Waste ADDITIONAL CATEGORIES Piping (70), Pressure Stress (109), Material Weight (101), Area Formulas (60), Flat Plates, Pumps, Pump Laws, Steam, Crusher, Vapor Separators, Equilibrium, Cogeneration, and more CONVERSIONS BTU, Cubic, Flows, Ft-Lbs, Horsepower, HVAC, Hydraulic, Linear, Liquid, Metric (460), Power, Pressures, Square Measures, Watts, Weights TEMPERATURE SCALES Celsius, Fahrenheit, Kelvin, Rankine, Reaumur, Newton, Delisle, Romer 14 REFERENCE TABLES Chemical Properties, Steam Tables, Pipe Schedules, Material Densities, pH Scale, Engineering Constants, Chemical Resistance, Water Quality, Critical Properties, Antoine Constants, Heat Transfer Coefficients, Dimensionless Numbers, Gas Properties, Flammability Limits FEATURES - US/Metric toggle with dual-unit display - Save calculations and favorites - Share and export results - Searchable reference tables - Dark mode interface - Works offline Don't see a formula you need? Email us and we'll include it in the next update.
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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
Supabase
TypeScript
Native Base
react-query
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.
