ReScript Schema

The fastest composable parser/serializer for ReScript (and TypeScript)

⚠️ Be aware that rescript-schema uses eval for parsing. It's usually fine but might not work in some environments like Cloudflare Workers or third-party scripts used on pages with the script-src header.

Highlights:

• Combines validation and transformation without a performance loss
• Can transform parsed value back to the initial format (serializing)
• Works with any Js value, not only Js.Json.t
• Support for asynchronous transformations
• Immutable API with both result and exception-based operations
• Easy to create recursive schema
• Detailed error messages
• Opt-in strict mode for object schema to prevent excessive fields and many more built-in helpers
• Opt-in PPX to generate schema from type
• Works with plain JavaScript/TypeScript too! You don't need to use ReScript
• The fastest composable validation library in the entire JavaScript ecosystem (benchmark)
• Small JS footprint & tree-shakable API (Comparison with Zod and Valibot)

Also, it has declarative API allowing you to use rescript-schema as a building block for other tools, such as:

• rescript-envsafe - Makes sure you don't accidentally deploy apps with missing or invalid environment variables
• rescript-json-schema - Typesafe JSON schema for ReScript
• Internal form library at Carla

Documentation

• For ReScript users
• For PPX users
• For JS/TS users
• For library maintainers