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
RF-Toolbox Pro
Specialized on high frequency electronics for RF professionals, radio amateurs and students.
$7.99 · In-app purchases
PRICE
$7.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.9
22 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 included17 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
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 RF-Toolbox Pro: 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 number of calculators and tools available.
Assumption to check: Limited calculators compared to competing apps
Validate with people who use this workflow before building.
Hypothesis 2
Implement a more organized and user-friendly layout.
Assumption to check: User interface can feel cluttered
Validate with people who use this workflow before building.
Hypothesis 3
Add cloud synchronization for user data and settings.
Assumption to check: Lack of advanced features like cloud sync
Validate with people who use this workflow before building.
Hypothesis 4
Introduce a free trial period to attract more users.
Assumption to check: No free trial option for users
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
Specialized on high frequency electronics for RF professionals, radio amateurs and students. RF-Toolbox is based on the popular Electronic Toolbox by Marcus Roskosch. This app contains some of the common tools of Electronic Toolbox but contains a wide range of additional tools, specialized for high frequency electronics, RF professionals, radio amateurs and students. Currently RF-Toolbox consists of more than 90 tools and like Electronic Toolbox, there are more to come over the time. Feature list: ■ PCB Trace Width (Internal and external Traces) ■ PCB Trace Resistance ■ PCB Trace Impedance (various trace types e.g. Microstrip, embedded Microstrip, Symmetric and Asymetric Stripline, Wire Microchip, Wire Stripline, Edge Coupled Microstrip and Stripline) PCB Crosstalk (Microstrip and Stripline) ■ LC L/T/Pi Match calculation ■ Coax Cable calculation (Standard and individual Types) ■ Amplifier and Attenuator cascade calculation ■ SWR / Reflection / Return loss conversion ■ Power Divider (Branchline, Ratrace and Wilkinson) ■ Capacitor Plate calculation ■ RLC Parallel, Series and Circuit calculation ■ Noise Figure conversion ■ Skin Depth calculation (various materials from Aluminum to Silver) ■ Butterworth Filter (also with plot of filter chart) ■ Chebyshev Filter (also with plot of filter chart) ■ R-C, L-C, R-L High/Low/Band-Pass Filter ■ RF Units conversion (quick conversion of frequently used units) ■ Air coil inductance calculation ■ Resistors, Capacitors, Inductors in Parallel / Series And there is much more... ■ Aktive Filter calculation tool ■ Antenna calculation tool ■ Delta Star calculation ■ Cable length / ampacity tool ■ PTC / NTC Temperature Resistance conversion ■ AC Ohms law tool ■ Zener diode circuit calculation ■ Constant current source tool ■ ASCII Table ■ Desktop calculator ■ Resistor/Capacitor/Inductor combinations tool ■ 4-20mA conversion tool ■ Passive cooling calculator ■ Audio Oscilloscope Please check out more screen shots on my website (WEBSITE Link on the left side). If you have questions, please feel free to contact me by using the Support button here, inside the App or on my website. Thank you! Marcus Roskosch
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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
Zustand
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react-native-gesture-handler
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.
