ButterKit is a native macOS app for Apple developers that automates the full App Store screenshot workflow — from Xcode Simulator capture and 3D device mockups to instant localization in 50 languages and one-click upload to App Store Connect.
What is ButterKit?
ButterKit is a desktop application built for macOS (requires macOS 26+, Apple Silicon recommended, Intel supported) that takes app screenshots as input — either captured directly from Xcode Simulator, dragged as PNG/JPG onto 3D device frames, or linked from a folder (e.g., Fastlane output) — and produces finalized App Store-ready images with multilingual metadata. It was built by solo developer Zach Spitulski, a design engineer based in Los Angeles.
Key Features
- Direct Xcode Simulator capture — Capture screenshots from Xcode Simulator with one click, eliminating manual screenshotting and file management. Learn more →
- Real 3D device frames — Place screenshots into photorealistic 3D devices (iOS, iPadOS, macOS, watchOS, visionOS, plus some Android). Rendering is built on Metal and runs up to 120fps.
- Instant translation to 50 languages — Translate screenshots and app metadata to all 50 App Store Connect localizations. Free on-device translation (Apple Silicon) supports 18 languages offline; cloud translation (Pro) uses your own API key for the full 50-language set. Learn more →
- App Store Connect upload — Upload designed screenshots and metadata (description, What's New, promotional text — Pro feature) directly via the official API. Learn more →
- Folder linking and Fastlane integration — Link a Fastlane screenshots folder so new captures automatically update your designs without manual file management. Learn more →
- AI/MCP automation — Built-in Model Context Protocol (MCP) server lets AI coding agents (Claude Code, Cursor, Codex) automate screenshot generation, translation, and publishing. Learn more →
- Pro editing tools — Use professional templates, custom fonts, gradients, backgrounds, and 3D callouts. Templates are bundled and a community marketplace is growing.
Who is it for?
- Indie Apple developers who need to prepare App Store screenshots and metadata for multiple languages without manual rework.
- Teams using Fastlane or CI/CD pipelines — Link a Fastlane screenshot folder and let ButterKit automatically update designs and upload to App Store Connect.
- Developers targeting global markets — Localize screenshots and metadata to all 50 App Store languages in seconds, using free on-device or cloud AI translation.
- AI agent users — Developers who want AI coding tools (Claude Code, Cursor) to automate the entire screenshot and publishing workflow via MCP.
What can you do with ButterKit?
- Capture and mockup in one step — Pull screenshots from Xcode Simulator into a 3D device frame, then adjust angles and backgrounds in real time.
- Translate and preview — Auto-translate all screenshot text and metadata, then see how your app's story will look on every device and language before publishing.
- Upload and ship — Export batches of images or push designs directly to App Store Connect — correct order, ready for review.
How does it work?
Drag screenshot images onto 3D device frames, or capture from Xcode Simulator with one click. Design using bundled templates or custom tools. Translate to 50 languages with on-device or cloud AI. Upload directly to App Store Connect via API. An MCP server allows AI coding tools to drive the entire pipeline.
