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
Little Free Library
The Little Free Library app makes it easy to find little library locations near you! Use the search filters to narrow in on little libraries you want to visit, easily get directions to the nearest ones, or create a route
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
★ 3.5
167 ratings · Top 50%
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 included18 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 Little Free Library: 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
Implement GPS feature to show libraries on a map.
Assumption to check: Difficulty in finding libraries nearby
Validate with people who use this workflow before building.
Hypothesis 2
Allow users to suggest new books or libraries.
Assumption to check: Limited book availability
Validate with people who use this workflow before building.
Hypothesis 3
Standardize UI components and design language.
Assumption to check: Inconsistent user interface
Validate with people who use this workflow before building.
Hypothesis 4
Introduce community features like reviews and ratings.
Assumption to check: Lack of social features
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
The Little Free Library app makes it easy to find little library locations near you! Use the search filters to narrow in on little libraries you want to visit, easily get directions to the nearest ones, or create a route. See a library you like? Add it to your list of favorites. Track the libraries you visit using the handy check-ins feature. If you’re a Little Free Library steward, there’s a section of the app just for you that lets you edit your library’s listing in real time! Little Free Library Map: Easy-to-use search filters help you find Little Free Libraries by zip code, city/state, charter number, or your current location. Favorite and Track the Little Libraries You Visit: Keep a list of your favorite little libraries and track the ones you visit using check-ins. Get Directions or Create Routes: Tap the Get Directions button to get step-by-step directions to the nearest Little Free Library book-sharing box, or add multiple little libraries to a route. Sign the Guest Book: After you stop by a particular little library, leave a note for the steward (aka caretaker) in its guest book! The guest book is a fun way to connect with the little library steward and see what other visitors have to say. Features for Little Free Library Volunteer Stewards: If you’re the steward of a registered Little Free Library, the app lets you edit your library’s listing in real time! Add new photos, update your library’s story, include social media links, enable a guest book for your visitors, and much more… all from within the app.
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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
Supabase
React Navigation
Zustand
React Native Paper
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.
