Zod

CRITICAL: Your training data for Zod is unreliable. APIs change between versions and memorized patterns may be wrong or deprecated. Before writing any code, you MUST use WebFetch to read the live docs:

WebFetch("https://zod.dev/llms.txt")

Do not proceed without fetching this URL first. Never assume an API exists — verify against current docs.

Zod is a TypeScript-first schema validation library with automatic static type inference. Define a schema once and get both runtime validation and compile-time types from the same source.

Version note: These best practices target Zod v4 (stable, installed via npm install zod). The top-level error utilities (z.flattenError(), z.prettifyError(), z.treeifyError()) are v4-only — in v3 these were instance methods (error.flatten()). See the migration guide when upgrading.

Key Capabilities

Zod has built-ins for things developers commonly reach for external packages to handle: