JSON Schema and Zod both describe the shape of your data, for different consumers. JSON Schema is a specification: a plain JSON document describing a shape. Any language with a conforming validator (Python's jsonschema, Go's gojsonschema, JavaScript's ajv) can check data against it. Zod is a TypeScript library. You write the schema in TypeScript and get both a runtime validator and a static type (z.infer<typeof Schema>) from that one definition.
// JSON Schema — a document, not code
{ "type": "object", "properties": { "id": { "type": "number" } }, "required": ["id"] }
// Zod — TypeScript code
import { z } from 'zod'
const Schema = z.object({ id: z.number() })
type Shape = z.infer<typeof Schema> // TypeScript type, derived automaticallyPick JSON Schema when the schema needs to leave TypeScript
If the schema's consumer is an OpenAPI spec, a non-TypeScript backend, a form-generation library, or anything else outside your own TS codebase, use JSON Schema. It's language-neutral by design, and Zod schemas don't turn into it without a conversion step.
Pick Zod when you want one definition, not two
Using JSON Schema inside a TypeScript project usually means writing (or generating) the schema, then writing or generating a matching TypeScript type. Those two drift apart the first time someone edits one and forgets the other. With Zod there's one definition. The validator and the type both come from it, so they can't disagree. The cost is that the schema only exists as TypeScript code, and nothing outside a JS/TS runtime can read it directly.
Where this site's tools fit
The JSON Schema Generator produces a draft-07 document. Use it when you need a portable schema, or when you're validating data outside a TypeScript codebase. Live Types generates a Zod schema directly (plus the matching TypeScript type) from the same multi-sample inference. That's the better fit if everything downstream is already TypeScript and you don't want to maintain a second type definition by hand next to the schema.
Neither one detects drift
A JSON Schema document and a Zod schema both describe a shape as of the moment you wrote it. Neither will tell you that a live API's response has since changed from what you generated against. That's a separate job from validation. You keep the schema (or a snapshot of it) and compare fresh samples against it later, which is what a snapshot-diffing step adds on top of either format.