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Paseri

A TypeScript parsing and validation library for structured data. Ensure that untrusted input from users or external APIs conforms to the expected format.

Why the name? It's the Japanese name for parsley (パセリ), and also a play on words on parse/parsing, which is the goal of this library.

Installation

deno add jsr:@vbudovski/paseri

bunx jsr add @vbudovski/paseri

pnpm i jsr:@vbudovski/paseri

yarn add jsr:@vbudovski/paseri

npx jsr add @vbudovski/paseri

Acknowledgements

Zod

Paseri is heavily inspired by Zod's expressive API. While Zod is the industry standard for general-purpose validation, Paseri was built to bring that same developer experience to performance-critical applications and environments where Zod's architecture may be a bottleneck — all while maintaining a zero-compromise approach to security.

Valita

Valita sets the high water-mark for performance in the TypeScript ecosystem¹. Paseri matches or exceeds this raw efficiency while offering a more expansive, Zod-like feature set, and a focus on schema immutability.

Goals

The list may be expanded over time, but for now the objectives are the following:

• Parsing and validation of untrusted input to ensure it conforms to the expected format. A successful result will be typed with the narrowest possible definition to obviate the need to do additional validation at the point of usage².
• High performance¹ and usability in a strict Content Security Policy (CSP) environment.
• An API that is reasonably close to that of Zod. One-to-one compatibility is not the intention.
• Immutability of schemas. This avoids a lot of bugs caused by mutating references to non-primitive types.

Documentation

https://paseri.dev

Developer guide

Paseri uses the Deno runtime rather than Node, and requires Deno 2.7 or later. Packages are published to the JSR registry only, and publishing is performed automatically by CI.

• paseri-lib contains the sources for the library.
• paseri-docs contains the documentation, built with Astro and Starlight.

Setup

After cloning the repository, be sure you set up the git hooks using the following command:

deno task init

Running tests

deno test -P

Running benchmarks

deno bench

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Footnotes

1. While higher performance is possible using dynamic code execution (JIT) or ahead-of-time (AOT) compilation, these approaches introduce security risks or added build complexity. ↩ ↩²

2. An excellent article on the concept of type-driven design. ↩