Exact

What is Exact?

Exact is a cross-platform application runtime that lets developers write an app once and run it natively on the web, macOS, iOS, and Linux. The project uses a small declarative language called Contract to describe interfaces, while data logic is written in TypeScript or Rust.

A Contract compiler converts the interface description into a compact execution plan. On the web, this plan becomes a single ES module backed by a roughly 20 KB runtime that drives the browser DOM. On desktop and mobile platforms, a Rust runner executes the same plan.

Each platform uses its own drawing tools, such as AppKit, UIKit, or a GPU painter, while a Rust layout kernel handles box calculations using CSS rules. The framework is designed to work with AI coding agents, which can generate, run, observe, and test applications across all supported targets. Exact is released under the MIT license.

Exact features

• Single codebase targeting web, macOS, iOS, and Linux
• Declarative Contract language for defining user interfaces
• Data logic written in TypeScript or Rust
• AI agent support for building and testing apps
• Native rendering via AppKit, UIKit, or GPU painter
• CSS-based layout kernel computed in Rust

Who uses Exact and for what

• Build a single application that deploys to browsers and native desktop/mobile environments
• Use AI coding agents to generate, run, and verify cross-platform apps automatically
• Create native iOS and macOS apps with shared business logic and UI definitions
• Develop lightweight web applications with a minimal runtime footprint
• Prototype interfaces quickly using a declarative language before implementing platform-specific logic

Exact FAQ

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