JSON to TypeScript

What this tool does

This tool turns a sample JSON document into ready-to-use type definitions in three of the most popular ecosystems: TypeScript interfaces, Go structs, and Zod schemas. Paste a real payload — an API response, a config file, a database row — and the generator walks the structure, infers the type of every field, and emits clean, idiomatic code you can drop straight into your project. Everything happens locally in your browser; no JSON is ever uploaded.

Writing types by hand from a large JSON blob is tedious and error-prone. A single typo in a field name or a wrong type annotation can cause hours of debugging. Generating types from the actual data you receive guarantees the shapes line up with reality, and it takes a fraction of a second.

JSON to TypeScript, Go & Zod explained

TypeScript interfaces describe the shape of objects at compile time. The generator produces one interface per object, names nested interfaces after their keys in PascalCase, and types arrays by their element type. For example, {"tags": ["a", "b"]} becomes tags: string[]. Original key names are preserved exactly, so the interface matches your JSON without remapping.

Go structs are the backbone of typed JSON handling in Go's encoding/json package. The generator emits exported structs with PascalCase field names and a struct tag that preserves the original JSON key, like Name string `json:"name"`. Whole numbers become int, decimals become float64, booleans become bool, and nested objects become their own named struct types. Common initialisms such as ID, URL, and API are uppercased to follow Go naming conventions.

Zod is a TypeScript-first schema validation library. Unlike a plain interface, a Zod schema validates data at runtime and lets you infer a static type with z.infer. The generator emits a z.object({ ... }) for each object, mapping primitives to z.string(), z.number(), z.boolean(), and z.null(), and arrays to z.array(...). This is the safest way to consume untrusted JSON, because malformed data is rejected before it reaches your code.

How to use it

1. Paste or type your JSON into the input panel on the left. A sample loads by default so you can see the output immediately.
2. Pick a target language — TypeScript, Go, or Zod — using the buttons at the top. The output recomputes instantly.
3. Set the root type name if you want something other than Root for the top-level interface or struct.
4. Click Copy to grab the generated code, then paste it into your editor.
5. Share your work by copying the address bar — the JSON and selected language are encoded in the URL.

Why generate types from JSON

Strong typing catches bugs before they ship. When you model an API response with hand-written types, you are guessing at the shape; when you generate types from a captured sample, you are documenting the shape that actually arrives. This matters most at integration boundaries — third-party APIs, webhooks, message queues — where the data is defined by someone else and can drift over time.

Generated types also serve as living documentation. A new teammate can read the interface or struct and understand the payload without digging through the producing service. And because the same JSON can produce TypeScript for the frontend, Go for a backend service, and a Zod schema for runtime validation, the three stay consistent with one source of truth: the data itself.

The tool infers types from a single example, so the result reflects exactly what you paste. If a field is sometimes absent or nullable, include a representative sample or tweak the output — add ? in TypeScript, omitempty in a Go tag, or .optional() in Zod. For deeply nested or recursive structures, the generator names sub-types after their parent keys to keep the output readable and collision-free.

Privacy and offline use

Because the generator is pure client-side JavaScript with no dependencies, your JSON never leaves the page. You can use it on an airplane, behind a corporate firewall, or with confidential payloads without any concern that data is being transmitted. There are no ads, no trackers in the conversion path, and no backend.

Frequently Asked Questions