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
Free Books - 23,469 Classics For Less Than A Cup Of Coffee. An Extensive Ebooks And Audiobooks Library
Free Books for iPhone is the world's favorite paid book app
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 3.1
56 ratings · Below Average
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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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/
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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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Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Free Books - 23,469 Classics For Less Than A Cup Of Coffee. An Extensive Ebooks : 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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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
Offer unique titles and user-driven recommendations.
Assumption to check: Limited selection of premium books compared to other apps
Validate with people who use this workflow before building.
Hypothesis 2
Implement better search and filtering options.
Assumption to check: Navigation can feel clunky with many books
Validate with people who use this workflow before building.
Hypothesis 3
Focus on a cohesive design system across all screens.
Assumption to check: Inconsistent user interface design
Validate with people who use this workflow before building.
Hypothesis 4
Simplify purchase flows and provide clearer value propositions.
Assumption to check: In-app purchase process can be confusing
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
Free Books for iPhone is the world's favorite paid book app. Browse our handpicked ebook collections, download any one of our 23,469 classic books instantly, and read with our fully featured ereader. On the go? We save your place in the book automatically. We've crafted handpicked collections to make browsing the extensive ebook library a snap, and commissioned hundreds of custom book covers to bring you Cover Mode. This is the world of public domain literature like never before. Unlike "free" apps that charge you $10 a book, with Free Books once you pay, everything's included. No limits! No download caps. 23,469 classics in your pocket, for less than a cup of coffee. Features: * Books. Free Books! The plays of Shakespeare, the letters of leaders, the autobiographies of Franklin and Carnegie, the collected works of geniuses, the philosophy of Seneca and Plato. It's all here in our library, along with tens of thousands of other books. * Handpicked Book Collections. English 101, Theology, Romance, Ghost Stories, Banned Books, Fiction, Novel ... the list goes on. We have 61 hand picked collections to make finding great books a cinch. * A Perfect Reader. It's beautiful, fast, and customizable. Curl up with a book in Night Mode, change font sizes with a tap, and turn the page with a simple swipe. You can even upload your own book from Dropbox in epub format. * Original Covers. We make public domain books come alive with absolutely beautiful covers. * Over 4,000 audiobooks featuring Librivox recordings can be unlocked to go along with the ebook collection. You can easily switch between ebook and audiobook versions while reading. If you have any questions or suggestions don't hesitate to drop us a line at [email protected] that's what we're here for! ***** FIVE STARS Great app! My pocket is a library and I love that you can have the book sent to your email. I will never get rid of this ***** LOVE IT! Love love love this app! There's book I can read to my kids, and there's tons of books for me. I don't go for "typical" recommended read, so I love that the classics and more unusual are @ my fingertips. More please! ***** VERY GOOD APPLICATION Use it every day. Have bought paperback versions of classics for $5. This is a bargain! ** above quotes are recent 5 star reviews on the app store **
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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
Zustand
Axios
React Navigation
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.
