wtf is zod-to-json-schema?

Zod-to-json-schema is a utility that translates data validation rules written in Zod (a popular TypeScript validation library) into JSON Schema, a widely-supported format for describing data structures. If your app already defines its data shapes using Zod, this tool lets you reuse those definitions anywhere JSON Schema is expected, without writing the same rules twice. At a practical level, you pass in a Zod schema and get back a JSON Schema object. For example, a Zod rule saying "this field is a string of at least 5 characters" becomes the JSON Schema equivalent with type: "string" and minLength: 5. The tool handles nested objects, unions (fields that accept multiple types), recursive schemas, and recurring schemas by using internal references so the output stays clean. It can also target OpenAPI 3 (the spec behind Swagger documentation) instead of standard JSON Schema, which is useful for generating API docs. A developer building a form library or API documentation might reach for this. If your frontend uses a form validator that consumes JSON Schema (like react-hook-form with AJV), you can keep your single source of truth in Zod and export it for the form. If you're generating OpenAPI docs for an API, the tool bridges your TypeScript types into that spec without manual duplication. It even supports carrying over custom error messages from Zod into the JSON Schema output, so validation feedback stays consistent across frontend and backend. The tool offers fine-grained control through an options object. You can choose how references are resolved, how dates are represented (string vs. Unix timestamp), how email validation is encoded, and which JSON Schema draft to target (draft-7 or 2019-09). A handful of known issues are noted in the README but are cut off before detailing them, so developers relying on edge cases like relative references or pipe strategies should check the project's issue tracker.