Show HN: Raincast – Describe an app, get a native desktop app (open source)

Describe an app. Get a native desktop app.

AI-powered app generator that builds real, shippable Tauri applications from natural language.

Raincast is a desktop application that generates other desktop applications. You describe what you want in plain English, and Raincast builds a fully functional native app: with a real UI, backend commands, file system access, and system integration. Not a mockup. Not a prototype. A compiled, shippable application.

It generates React + Tauri apps with:

• 9 layout templates: dashboard, editor, chat, file manager, media player, data table, playground, utility, and generic
• Rust backend: AI writes Tauri commands for file I/O, shell execution, system monitoring, network calls
• Native window chrome: transparent backgrounds, macOS vibrancy, overlay title bars, custom window sizes
• Live preview: see your app running as it's being built, with hot reload
• One-click ship: compile to a standalone binary you can distribute

You describe what you want, and Raincast generates the full app: React frontend, Rust backend commands, and Tauri config.

The interesting part is how the live preview works. Generated apps call Rust backend commands via Tauri's invoke() bridge, but in dev mode the full Tauri binary isn't compiled yet. So Raincast builds a proxy binary: it parses the generated Rust source using AST extraction to find every #[tauri::command] function, then generates a standalone CLI binary that reads JSON from stdin, dispatches to the same functions, and writes JSON to stdout. The frontend's invoke() calls get routed through this proxy instead of the real Tauri runtime. This means the preview behaves like the real app: file system access, shell commands, system info all work during development, not just after shipping.

When you hit Ship, Raincast compiles the actual Tauri binary with all the real commands baked in. The proxy is only for dev.

Raincast supports multiple AI backends including Anthropic Claude (Sonnet 3.5, Haiku 3.5) and Google Gemini (1.5 Pro, 1.5 Flash). Users bring their own API keys.

Example Use Cases:

• Utility Apps: Compact tools like VPN status monitors with frosted glass windows.
• Full Applications: Local AI chat interfaces connecting to llama.cpp servers.
• Games: Side-scrolling platformers with HUDs and particle effects.
• Automation: File organizers that watch folders and auto-sort files.

Raincast is open-source under the MIT license and supports macOS, Windows, and Linux.