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
OldTimer Rally Timer
OldTimer Rally Timer is the ultimate app for classic car rally enthusiasts
$3.99 · In-app purchases
PRICE
$3.99
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.
Build your own version
Build Kit
Make this idea yours
A product spec, screen plans, and build steps for your coding agent.
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Combine features and design from your favorite apps.
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What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
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/
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 OldTimer Rally Timer: map the core Navigation 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
Allow users to customize stages with more detailed settings.
Assumption to check: Lack of customization options for rally stages
Validate with people who use this workflow before building.
Hypothesis 2
Implement offline mode to access saved stages without internet.
Assumption to check: No offline functionality
Validate with people who use this workflow before building.
Hypothesis 3
Add a review system for users to provide feedback on their experience.
Assumption to check: Limited user feedback options
Validate with people who use this workflow before building.
Hypothesis 4
Integrate maps for better navigation and stage tracking.
Assumption to check: No integration with maps or GPS 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
OldTimer Rally Timer is the ultimate app for classic car rally enthusiasts. Developed by rally drivers for rally drivers. KEY FEATURES: • GPS-based distance measurement with highest precision • Section timers with start/stop functionality • Multiple simultaneous timers for different sections • Roadbook scanner for digital navigation • Average speed tables • Detailed rally logs and results • CSV export for analysis • iOS widgets for quick access • Works completely offline PROFESSIONAL FEATURES: • Calibratable distance measurement • Flexible timer start modes (manual, scheduled, GPS movement) • Live Activities for active sections • Background GPS tracking • Metric and imperial units • Precision settings up to 3 decimal places EASY TO USE: The intuitive user interface enables quick operation even while driving. Large, easily readable displays and simple touch operation guarantee maximum safety. PRIVACY: All data stays on your device. No cloud connection, no data collection, complete privacy guaranteed. Perfect for TSD rallies, regularity trials, and classic car events. Terms of Use (EULA): https://couture-pixels.de/djai/djai-eula.html
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
React Navigation
Async Storage
react-native-sound
BUILD KIT DIFFICULTY
Advanced
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.
