JavaScript schema library from the Future

ReScript Schema - The fastest parser in the entire JavaScript ecosystem with a focus on small bundle size and top-notch DX. Why did you not hear about it then, and why should you learn about it now? I started developing the library three years ago, and today, it's at a point others have yet to achieve. I'll prove it in the article, but before we start, I'd like to answer a few questions you might already have. What's a parser? One of the most basic applications of ReScript Schema is parsing - Accepting unknown JavaScript data, validating it, and returning the result of your desired type. There are dozens of such libraries, and the most popular ones are Zod, Valibot, Runtypes, Arktype, Typia, Superstruct, Effect Schema, and more. Also, even though this is slightly different, validation libraries like Ajv, Yup, and others also stand really close. Is ReScript Schema faster than all of them? Yes. It's ~100 times faster than Zod and on par with Typia or Arktype (benchmark). But often, besides validation, you want to transform data incoming to your system, and here, ReScript Schema overperforms any solution existing in the JavaScript ecosystem. What's ReScript? Isn't the library for JavaScript/TypeScript? ReScript is a robustly typed language that compiles to efficient and human-readable JavaScript. And yes, ReScript Schema is written in ReScript, but it also has a really nice JavaScript API with TS types. You don't need to install or run any compiler; npm i rescript-schema is all you need. It makes ReScript Schema support 3 languages - JavaScript, TypeScript, and ReScript. This is especially nice when you mix TypeScript and ReScript in a single codebase

Feb 21, 2025 - 19:31

JavaScript schema library from the Future

ReScript Schema - The fastest parser in the entire JavaScript ecosystem with a focus on small bundle size and top-notch DX.

Why did you not hear about it then, and why should you learn about it now? I started developing the library three years ago, and today, it's at a point others have yet to achieve. I'll prove it in the article, but before we start, I'd like to answer a few questions you might already have.

What's a parser?

One of the most basic applications of ReScript Schema is parsing - Accepting unknown JavaScript data, validating it, and returning the result of your desired type. There are dozens of such libraries, and the most popular ones are Zod, Valibot, Runtypes, Arktype, Typia, Superstruct, Effect Schema, and more. Also, even though this is slightly different, validation libraries like Ajv, Yup, and others also stand really close.

Is ReScript Schema faster than all of them?

Yes. It's ~100 times faster than Zod and on par with Typia or Arktype (benchmark). But often, besides validation, you want to transform data incoming to your system, and here, ReScript Schema overperforms any solution existing in the JavaScript ecosystem.

What's ReScript? Isn't the library for JavaScript/TypeScript?

ReScript is a robustly typed language that compiles to efficient and human-readable JavaScript. And yes, ReScript Schema is written in ReScript, but it also has a really nice JavaScript API with TS types. You don't need to install or run any compiler; npm i rescript-schema is all you need.
It makes ReScript Schema support 3 languages - JavaScript, TypeScript, and ReScript. This is especially nice when you mix TypeScript and ReScript in a single codebase