is-kit is a lightweight, zero-dependency toolkit for building reusable TypeScript type guards.

It helps you write small isFoo functions, compose them into richer runtime checks, and keep TypeScript narrowing natural inside regular control flow.

Runtime-safe 🛡️, composable 🧩, and ergonomic ✨ without asking you to adopt a heavy schema workflow.

• Build and reuse typed guards
• Compose guards with and, or, not, oneOf
• Validate object shapes and collections
• Parse or assert unknown values without a large schema framework

📚 Documentation Site

Best for app-internal narrowing, filtering, and reusable guards.

Tired of rewriting the same isFoo checks again and again?

is-kit is a good fit when you want to:

• write reusable isX functions instead of one-off inline checks
• keep runtime validation lightweight and dependency-free
• narrow values directly in if, filter, and other TypeScript control flow
• compose validation logic…