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.
The platform board for your pocket.
$1.99 · 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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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 Tubbie: map the core Travel 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: Difficulty in finding suitable listings
Validate with people who use this workflow before building.
Hypothesis 2
Assumption to check: Inconsistent user reviews
Validate with people who use this workflow before building.
Hypothesis 3
Assumption to check: Limited communication with hosts
Validate with people who use this workflow before building.
Hypothesis 4
Assumption to check: Hidden fees during booking
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.
The platform board for your pocket. You already know the route. What you need at 8:47am (standing at the top of the stairs, or even before you leave your house) is one answer: is my train coming? Tubbie shows what your station's board shows. Every line, every direction, the way the platform boards do it. On your Lock Screen while you're walking. In a widget while your phone sits on your desk. Without opening anything. FEATURES • Board view: every train at your station, grouped by line and direction. Bakerloo, Central, Circle, District, Elizabeth, Hammersmith & City, Jubilee, Metropolitan, Northern, Piccadilly, Victoria, Waterloo & City, DLR, and the six named Overground lines. • Lock Screen Live Activity: tap a train and the countdown appears on your Lock Screen and in the Dynamic Island. When the train is gone, the activity ends itself — no stale countdowns, no manual cleanup. • Home Screen Arrivals widget: pick a station and a direction; it shows what's coming next, with a per-station direction picker that learns which directions your station actually serves. • Home Screen Status widget: every line's disruption state at a glance, so you see trouble before you leave. • Lock Screen widgets: accessory widgets (rectangular, circular, and inline) so the next train is visible on your Lock Screen even without a Live Activity running. • watchOS companion: the station arrivals board and the soonest upcoming train, right on your wrist. Requires watchOS 10.0 or later. • Watch complications: four families — circular, corner, inline, and rectangular — each showing the time until the next train with a per-second countdown on the watch face. • Status view: every line, every disruption status, before you go underground and find out the hard way. • Four themes: classic amber, orange, white, and a high-contrast theme designed for outdoor reading and low-vision users. • iOS 26 fluid tab bar with Liquid Glass refractive lensing (degrades cleanly to a Material pill on iOS 17–25). PRIVACY The platform board at your station doesn't need your email address. Neither does Tubbie. No accounts. No analytics SDK. No crash-reporting service. No advertising network. No third-party trackers. No push tokens sent anywhere. There is no server that knows you installed this app. Your TfL API key lives in the iOS Keychain and talks only to api.tfl.gov.uk. Location is requested once if you tap "Find nearest station," used immediately, and never stored. SETUP Tubbie uses the free TfL Open Data API. Get a key in two minutes at api-portal.tfl.gov.uk, paste it into Tubbie's settings, and the board lights up. The same key powers the Live Activity, widget, and Status view. If you're visiting London and need routing help, Citymapper will serve you better. Tubbie is for commuters who already know the way. ATTRIBUTION Tubbie is an independent project and is not affiliated with, endorsed by, or connected to Transport for London. Powered by TfL Open Data. Contains OS data © Crown copyright and database rights 2016.
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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.