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.
Is there fog where you are — and will you actually see the sun today? The Karl answers that one question honestly, with real satellite data instead of guesses.
$9.99 · 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 The Karl: map the core Weather workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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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 locations for weather data
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: Push notifications can be intrusive
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: In-app purchase model can confuse users
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: Radar map performance may lag
Validate with people who use this workflow before building.
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Is there fog where you are — and will you actually see the sun today? The Karl answers that one question honestly, with real satellite data instead of guesses. Named for Karl the Fog, San Francisco's most famous resident, this is a premium, dark-mode weather tool built for people who live and die by the marine layer. No cartoon animations, no simulated cloud graphics — just live NASA GOES-West satellite imagery, NOAA Bay visibility sensors, airport METAR reports, and real forecast models, fused into one honest verdict on your sky. Real data, radically transparent. Every layer in The Karl is sourced from an actual feed, and a dedicated Live Data Sources screen shows you exactly what each sensor is reporting right now. Scrub back through a 15-minute radar timeline to watch the fog bank move in real time. A sky verdict you can trust. The Karl fuses fog and cloud cover so an overcast day never reads as 'Clear.' You get a direct, plain-English answer to 'will I see the sun today?' — including burn-off times, not vague icons. Machine learning that actually learns you. Every forecast The Karl makes is graded against fresh data 30–60 minutes later, and your quick 'look outside' reports train a private, on-device correction tuned to your specific 25 km microclimate. The longer you use it, the better it gets — and your data never leaves your device. Find Sun, not just weather. Search real parks, beaches, viewpoints, and trails within 25 miles, ranked live by actual sun conditions, then jump straight into Apple Maps for turn-by-turn directions. Built for your whole day. Six map layers — Fog, Clouds, Fog + Clouds, raw satellite, Air Quality, and Visibility — plus Favorites, a Lock Screen Live Activity that counts down fog rolling in or burning off, Home Screen widgets that work offline, and a full Apple Watch app with its own fog dial and Find Sun page. The fog isn't going anywhere. Stop guessing and start knowing. Download The Karl.
Written user reviews are not shown here. Check current App Store reviews >
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.