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
Crystal Adblock – Block unwanted ads!
Start blocking ads on Safari immediately
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 2.7
278 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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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/
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 Crystal Adblock – Block unwanted ads!: map the core Utilities 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
Focus on optimization and stability to improve user experience.
Assumption to check: Low app rating (2.7/5) due to bugs and performance issues.
Validate with people who use this workflow before building.
Hypothesis 2
Provide users with advanced filtering options and customization settings.
Assumption to check: Limited customization options for blocking.
Validate with people who use this workflow before building.
Hypothesis 3
Include an onboarding tutorial to guide users through app features.
Assumption to check: Lack of clear instructions for new users.
Validate with people who use this workflow before building.
Hypothesis 4
Maintain a consistent design language throughout the app to enhance usability.
Assumption to check: Inconsistent UI design across screens.
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 blocking ads on Safari immediately. Ad blocking loads pages 4x faster, saves up to 50% of your data and much more! Crystal Adblock is easy to use and makes the browsing experience on your iPhone and iPad much more enjoyable. *Block all annoying ads on your iPhone and iPad* Ads will no longer clutter the small screen of your mobile device. Browse your favorite webpages without distractions from annoying banners and pop-ups. *Save up to 50% of your data* Ads can consume a really high percentage of your data plan. By blocking ads, Crystal Adblock helps to optimize the usage of your data for the online activities that matter to you. *Load pages 4x faster & enhance battery life* Browsing is sped up considerably with Crystal Adblock. The duration of your device’s battery life is also rapidly improved. *Stay safe and secure* Did you know that ads can hide malware and tracking? Protect yourself from these risks by using Crystal Adblock. A few words from satisfied users: ***** I couldn't be more pleased with how well this app performs ***** Simple, cheap and does what it says it does. Can't get better than that!! ***** Completely satisfied! You won't regret buying this app for less than a dollar. ***** Makes the Internet usable again . ***** SO NECESSARY Get Crystal Adblock now and enjoy ad-free browsing! Discover more at http://crystalapp.co Facebook: https://www.facebook.com/crystalapp Twitter: @_CrystalApp
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
React Navigation
Axios
Async Storage
TypeScript
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.
