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
KanjiBox
KanjiBox is an offline Japanese studying application
$4.99 · In-app purchases
PRICE
$4.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.6
132 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 included17 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 KanjiBox: map the core Education 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
Provide deeper insights and usage examples for each Kanji.
Assumption to check: Limited explanation for Kanji meanings
Validate with people who use this workflow before building.
Hypothesis 2
Incorporate gamification elements to enhance engagement.
Assumption to check: Lack of interactive features like games
Validate with people who use this workflow before building.
Hypothesis 3
Create forums or chat features to connect learners.
Assumption to check: No community features for learners
Validate with people who use this workflow before building.
Hypothesis 4
Enable full offline access for downloaded Kanji and quizzes.
Assumption to check: Poor offline support for studying
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
KanjiBox is an offline Japanese studying application. It provides an efficient yet fun way to practice all aspects of Japanese (kana, kanji, vocab, reading, writing...) through drills, quizzes and flashcards, while providing engaging feedback through progress charts, scores and game-like "achievements" for each Japanese level. KanjiDraw and KanaDraw add-ons harvest the full power of your device's touchscreen to guide you through proper Japanese handwriting, while detailed animated cards tell you everything you need to know on each kanji. KanjiBox is particularly well suited for standardized test preparation (JLPT, Kanji Kentei, Ninja Academy etc.) but works great as a personal study tool too. Main features: • Six training levels: JLPT N5 to JLPT N1, plus an extra "Sensei" level. • Adaptative learning: focuses on your weak points and uses spaced repetition (SRS) techniques to help you learn faster. • Live stats: let you measure your current level and gauge your progress. • Additional modules help you train your handwriting on kana and kanji using the touchscreen. • Custom Study Sets let you pick your own set of vocabulary words or kanji to focus on. • Over 6,000 kanji. • Over 34,000 vocabulary words. • Hiragana and katakana. • Drill mode helps you train on kanji, vocabulary, word reading and kana. • Quiz mode lets you log high scores and compete against friends. • Study mode gives you customisable sets of flashcards.
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.
SUGGESTED BUILD STACK
React Native
Expo
Supabase
Zustand
react-navigation
@supabase/supabase-js
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.
