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
ButterKit: Screenshot Studio
ButterKit helps app developers reach more users faster
Free · In-app purchases
PRICE
Free
In-app purchases
BUSINESS MODEL
Freemium
No overall Grossing estimate available
RATING
N/A
No ratings yet
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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Combine features and design from your favorite apps.
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What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
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 ButterKit: Screenshot Studio: map the core Developer Tools 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
Enhance editing capabilities with more tools like text and shapes.
Assumption to check: Limited editing features compared to desktop tools
Validate with people who use this workflow before building.
Hypothesis 2
Integrate sharing to social media platforms directly from the app.
Assumption to check: Lack of social sharing options
Validate with people who use this workflow before building.
Hypothesis 3
Provide users with the option to save screenshots in the cloud.
Assumption to check: No cloud storage for backups
Validate with people who use this workflow before building.
Hypothesis 4
Optimize the app for better performance across all devices.
Assumption to check: Inconsistent performance on older devices
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
ButterKit helps app developers reach more users faster. Quickly create stunning screenshots for the App Store; capture straight from Xcode Simulator, edit with 1-click templates and 3D devices, localize to all 39 App Store Connect languages, and upload/export. It’s fast and private with no accounts or ads. Apple M1 or newer is recommended for best performance (Intel works too). KEY FEATURES • App Store Screenshot Design Studio: pro typography, gradient tools, and precise 3D device controls (style, bezel, rotation, scale) • Professional Templates: designer-built layouts make screenshots look polished in minutes • Capture from Xcode Simulator: pull your app screenshots directly from Xcode Simulator into photorealistic 3D devices • Automatic Translations: use built-in translations for 20+ languages, or bring your own OpenAI API key to translate to all 39 supported ASC languages (Pro feature) • Automatic App Store Connect Uploading and Batch Image Exports • Built for Real Workflows: infinite canvas, keyboard shortcuts, undo/redo, file saving, custom fonts, gradients, and style presets. • Mac-native, Metal-accelerated: buttery-smooth editing with a realtime 3D renderer and lifelike iPhone, iPad, and Mac device frames. • Private by Design: all core features run on-device. Optionally use your own API keys for additional translation options (Pro feature) BUILT FOR DEVS & DESIGNERS ButterKit streamlines the full pipeline from capture, edit, translate, and export - so you spend time refining your product, not wrangling artboards. REALTIME 3D, ZERO WAIT Rotate, frame, and light photorealistic devices in a GPU-powered viewport. What you see is what you ship: responsive, precise, and smooth. LOCALIZE IN MINUTES Translations automatically respect typographic rules and constraints, keeping captions readable and aligned across all localizations. PRO FEATURES • Available as a one-time purchase or subscription • Remove "Made with ButterKit" watermark • Publish metadata directly to App Store Connect • Unlock OpenAI API usage for translations to all 39 App Store Connect languages Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
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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
react-navigation
@react-native-community/canvas
expo-image-picker
BUILD KIT DIFFICULTY
Advanced
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.
