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
Libby, the library app
Libby connects you to your local library’s collection of ebooks, audiobooks, magazines, and more
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.9
4,600,993 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 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 Libby, the library app: map the core Books workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
Screenshots
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App Store description
Libby connects you to your local library’s collection of ebooks, audiobooks, magazines, and more. With just your library card, you can instantly read or listen to books on your phone or tablet — for free, thanks to your public library! Browse and borrow everything from timeless classics to the latest New York Times bestsellers, and enjoy your next great read anytime, anywhere. What You Can Do with Libby - Browse your library’s digital catalog of books - Borrow and enjoy ebooks, audiobooks, and magazines - Send ebooks to your Kindle (U.S. libraries only) - Listen to audiobooks through Apple CarPlay - Download titles for offline reading, or stream them to save space - Use tags to create to-be--read lists or organize your favorite titles - Keep your reading position with automatic syncing across all your devices A Beautiful Reading Experience Enjoy a seamless reading experience with Libby’s elegant, easy-to-use ebook reader: - Adjust text size, background color, and book design to fit your preferences - Zoom into magazines, comics, and graphic novels - Define and search for words or phrases instantly - Read and listen to interactive read-alongs with your kids - Add bookmarks, notes, and highlights to personalize your reading An Immersive Audiobook Player Libby’s audiobook player makes listening effortless and enjoyable: - Slow down or speed up playback (0.6x to 3.0x) - Set a sleep timer for nighttime listening - Swipe easily to skip forward or backward - Add bookmarks, notes, and highlights as you listen Read Anywhere, Anytime Libby is designed for everyone, including kids, teens, and adults. Whether you’re exploring new stories, catching up on bestsellers, or revisiting your favorite books, Libby keeps reading simple, fun, and accessible. Built by OverDrive, Libby proudly supports public libraries and the joy of reading for all. Download Libby today and turn your device into your personal library.
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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 more personalized recommendations or partner with more libraries.
Assumption to check: Limited selection of titles compared to physical libraries.
Validate with people who use this workflow before building.
Hypothesis 2
Implement better notifications and reminders for due dates.
Assumption to check: Difficult to manage holds and due dates.
Validate with people who use this workflow before building.
Hypothesis 3
Simplify navigation and enhance onboarding for new users.
Assumption to check: Users find navigation confusing.
Validate with people who use this workflow before building.
Hypothesis 4
Clarify premium features and make the in-app purchase process more transparent.
Assumption to check: In-app purchase confusion regarding premium features.
Validate with people who use this workflow before building.
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
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BUILD KIT DIFFICULTY
Starter
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.
