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
FreeBooks: 76,000 Top Reads
Start reading in seconds — for free
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 4.7
2,977 ratings · Top 15%
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 included19 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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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 FreeBooks: 76,000 Top Reads: 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 exclusive content or partnerships with authors.
Assumption to check: Limited selection of books compared to paid services.
Validate with people who use this workflow before building.
Hypothesis 2
Provide an ad-free experience with a premium subscription.
Assumption to check: In-app ads can disrupt reading flow.
Validate with people who use this workflow before building.
Hypothesis 3
Implement better categorization and filtering options.
Assumption to check: Difficult to navigate large libraries.
Validate with people who use this workflow before building.
Hypothesis 4
Simplify subscription tiers and clearly communicate benefits.
Assumption to check: Subscription management 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
Start reading in seconds — for free. From swoon-worthy romances to addictive thrillers, gripping dramas to riveting mysteries—there’s something for everyone. Save, download, and read anywhere. Find your next read faster - Browse trending picks, search by genre or author, and get personalised recommendations. Key Features - 76,000+ Books: Explore a huge library across all genres. - Powerful Search: Quickly find books by title, author, genre, or category. - Personalised Reading: Customise fonts, text size, and background themes. - Your Library: Save and organise favourites for quick access. - Offline Reading: Download books and read without an internet connection. Why FreeBooks? - Vast Selection: From modern bestsellers to timeless classics (Austen, Brontë, Shakespeare). - Fresh Updates: Our team adds new books daily, keeping your library fresh and exciting. - Curated Recommendations: Discover popular and trending books tailored to your interests. - Community Favourites: Explore what other readers are enjoying and join a global community of book lovers. Perfect for Every Reader - Whether you’re a student, lifelong learner, or casual reader, FreeBooks lets you explore, organise, and enjoy literature your way. Build your digital library, dive into classics, or find your next modern favourite. FreeBooks+ - Reading is available without a subscription. FreeBooks+ removes ads and unlocks extra features. Subscriptions auto-renew unless canceled at least 24 hours before the end of the current period. Manage or cancel anytime in your Apple ID account settings. Terms: https://freebooksapp.org/terms Privacy: https://freebooksapp.org/privacy
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.
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BUILD KIT DIFFICULTY
Expert
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.
