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
What Is My Speed?
Track your speed on your iPhone while driving, bicycling, running or walking.
$2.99 · In-app purchases
PRICE
$2.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 5.0
2 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.
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 included15 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 What Is My Speed?: 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
Provide detailed analytics and visual graphs of speed history.
Assumption to check: Limited historical data viewing options
Validate with people who use this workflow before building.
Hypothesis 2
Implement calibration options for improved accuracy.
Assumption to check: Inconsistent GPS accuracy
Validate with people who use this workflow before building.
Hypothesis 3
Add offline mode to store speed records locally.
Assumption to check: No offline functionality
Validate with people who use this workflow before building.
Hypothesis 4
Allow users to customize UI themes and layouts.
Assumption to check: Limited customization options 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
Track your speed on your iPhone while driving, bicycling, running or walking. See your course and altitude at all times. Optionally set a speed limit and get audible and visible warnings on your iPhone when you exceed it. Reduce the speed limit to zero or extend it over the maximum to turn off speed limit warnings. Designed for easy viewing in all light conditions and with very accessible swiping to change the speed limit quickly and easily. If you want more detailed information, tap the info button to see a complete list of available data about your current location. Your current iPhone settings are used to set the default units for speed and altitude, but these are easily changed after tapping the info button. To adjust the speed limit, swipe from side to side. Or tap the speed limit indicator to expand it for easier viewing and then swipe to increase or decrease the speed limit. Tap again to shrink the speed limit indicator or leave it for a few seconds and it will shrink automatically. Use the slider to adjust the screen brightness for maximum visibility. No ads, no in-app purchases - you get the complete app for the price of a cup of coffee.
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
Expo Location
React Navigation
React Native Chart Kit
Zustand
Axios
Shadcn/UI
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.
