Convert a JSON sample into TypeScript types and a Zod schema locally. Handle nested objects, mixed arrays, nulls and optional keys.
How to convert JSON into code
Paste valid JSON, choose a root type name such as UserResponse, and select TypeScript, Zod or both. Press Generate to create editable code. Use Load example if you want to see how nested arrays behave before using your own sample. Copy the result or download it as a .ts file. The tool does not fetch an API response; it only works with the text you supply.
What the converter infers
JSON strings become string types, numbers become number, booleans become boolean and null stays null. Nested objects are handled recursively. For an object at the root, the TypeScript output uses an interface; root arrays and primitive values use a type alias. The Zod output imports z from your own installed zod package and builds a matching runtime schema.
Mixed arrays and missing properties
The converter examines every observed array element. Different primitive types create a union. When objects in the same array have different keys, a key absent from one object becomes optional. For example, [{"id":1,"name":"Ada"},{"id":2}] produces an optional name field. Empty arrays have no evidence about their element type, so their elements are unknown. An empty object also needs review before you treat it as a complete contract.
Sample data is not an API specification
A single example cannot reveal every allowed value. A field that is always present in your pasted sample could still be optional in production. A number might need a minimum, a string might be an email, and a property might be restricted to an enum. This converter does not invent such rules. Date-like strings remain strings, and it does not infer discriminated unions or relationship constraints.
Names, large IDs and safe output
Choose a valid non-reserved TypeScript identifier of up to 50 characters. Property keys are quoted, and Zod keys use computed property notation so unusual names such as __proto__ are emitted safely. Integers outside the JavaScript safe integer range are rejected; store those IDs as JSON strings to preserve them. Invalid JSON, non-finite numbers, excessive nesting and oversized inputs produce a visible error.
Privacy and project integration
Conversion happens in your browser without an external API, AI service or upload. The tool does not save your JSON in local storage. Your site session and ordinary website analytics are separate from the converter. In your project, install a compatible Zod version, inspect the generated code, add domain rules and test both valid and invalid data. The output is a starting point, not proof that your whole API is validated.
Advice
Keep the original input and inspect the generated result before using it in a real project.
Frequently asked questions
Does it fetch an API response?
No. Paste a JSON sample yourself.
Why is a field optional?
It was absent from at least one observed object in the same array.
Does an empty array reveal its element type?
No. The output uses unknown until you supply examples.
Can I use the schema immediately?
Review it, add domain constraints and test it in your project first.