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.
Mud Engineer App – Drilling Fluids Calculator
$2.99 · In-app purchases
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.
A product spec, screen plans, and build steps for your coding agent.
First kit free with a verified email
Combine features and design from your favorite apps.
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Generating… usually about a minute.
What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
A product spec, phased build plan, differentiation notes, and screen references.
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Goal: Send a clear invoice after finishing a job.
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.
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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Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
Rork plan preview for Mud Engineer: map the core Business workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Mud Engineer App – Drilling Fluids Calculator Mud engineers play a crucial role in keeping drilling programs running smoothly. The Mud Engineer App is an essential field tool that gives you 14 drilling-fluid and well-control calculators in one place, built for rig work: fast input, clear step-by-step equations, professional PDF reports, and full offline use. CALCULATORS • Final Mud Weight – mix two fluids and get the resulting weight and volume • Volume – volumes of two fluids needed to build a required volume at a target weight • Reduce Mud Weight – barrels of a lighter fluid (water, seawater, diesel) to dilute the mud • Weight Up – sacks, lb/bbl, total material, volume increase and final volume (barite, CaCO3, hematite) • Hydrostatic Pressure and pressure gradient • Equivalent Circulating Density (ECD) • Annular Velocity • Triplex Pump Output – bbl/stroke, bbl/min and flow rate • Kill Sheet – Kill Mud Weight, ICP and FCP, with safety margin • Bottoms Up – annular volume, strokes and time • Pipe Capacity & Displacement – open-ended and closed-end • Oil/Water Ratio – from retort readings, with oil or water to add to reach a target ratio • Rheology – PV, YP, apparent viscosity, n and K from Fann 600/300 readings • EMW & Pressure Gradient BUILT FOR THE FIELD • Step-by-step worked equation with your own numbers, plus the formula reference • Change units right inside each field – values convert automatically • Quick-value chips: barite, CaCO3, hematite, water, seawater, diesel, sack sizes, pump efficiency • Smart checks catch unit slips (e.g. 35 typed into an SG field) and impossible inputs • Values carry over between calculators: pump output feeds Bottoms Up and Annular Velocity, the new mud weight feeds Hydrostatic, ECD and Kill Sheet WELLS & HISTORY • Manage multiple wells (name, rig, field); each well keeps its own calculations and values • Every calculation is saved automatically in a searchable history, filtered by well, date or calculator • Export history to CSV (Excel) or a combined PDF PROFESSIONAL PDF REPORTS Input and result tables, the worked equation, the reference, the well, your name or company, the date and an app watermark – ready to share. UNITS & SETTINGS • Oilfield and metric units: ppg, SG, g/cm³, kg/m³, pcf, bbl, m³, gal, L, ft, m, in, mm, psi, bar, kPa, gpm, L/min, bbl/min, m³/min • Exact unit conversions • English and Arabic interface • Favorites and search on the home screen • Adjustable decimal places, light or dark theme • Works fully offline – no account, no ads, your data stays on your device Formulas follow standard oilfield references (Lapeyrouse, Formulas and Calculations for Drilling; IWCF kill sheet; API RP 13B) and are verified against published worked examples. Special thanks to Eng. Mahmoud Elbeltagy for contributing to the development of these calculations.
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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
Assumption to check: Limited functionality for complex calculations
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: Cluttered UI with mixed elements
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: Poor customer support and updates
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: Subscription model lacking clear value
Validate with people who use this workflow before building.
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
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.