Introduction

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Motivation

• Generate instantly re-usable TypeScript types from backend endpoints – enabling full-stack development without build steps.
• Strong static typing with aggressive inference and smart narrowing – so you move fast while staying safe.
• Data types that automatically validate deeply nested input data – to keep untrusted user input out of your application logic.

type PlaceOrderInput = {
	stockKeepingUnit: String.Min(1).Max(64),
	quantity:         Int.Min(1).Max(99),
}

func placeOrder(in: PlaceOrderInput) {
	// in is already validated; business logic starts here
}

// forst build
type PlaceOrderInput struct {
	stockKeepingUnit string
	quantity         int
}

func placeOrder(in PlaceOrderInput) {
	if len(in.stockKeepingUnit) < 1 || len(in.stockKeepingUnit) > 64 { ... }
	if in.quantity < 1 || in.quantity > 99 { ... }
	// business logic starts here
}

// forst generate → generated/types.d.ts
export interface PlaceOrderInput {
  quantity: number;
  stockKeepingUnit: string;
}

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How it fits your stack

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Start here

Why Forst?

Design priorities and what Forst omits.

Quickstart

Install, write your first .ft file, run it.

Language overview

Aligned with Go, structural typing, explicit control flow.

Validated shapes

Types as schemas with built-in constraints.

Mix with Go packages

Import Go packages. Mix .ft with .go.

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Examples and packages

• Compiler examples: github.com/forst-lang/forst/tree/main/examples/in
• npm compiler: @forst/cli
• Gradual adoption: @forst/sidecar, for invoking Forst from Node during migration