Does this tool send my JSON anywhere?

No. Parsing and code generation both happen in your browser with JavaScript. Nothing is uploaded to a server.

How are nested objects handled?

Each nested object gets its own dataclass, named after the parent field, and is referenced as a typed field in the parent dataclass.

What happens with an array of mixed types?

If array elements are not all the same type, the field is typed as List[Any] with a comment noting the mixed contents.

What if a JSON value is null?

A null value is typed as Optional[Any] since the tool cannot infer a concrete type from null alone.

Does it support JSON arrays at the top level?

Yes. A top-level array is wrapped as a List[...] of the generated root dataclass, or a list of primitives if the array holds primitive values.

Can I use the output with Pydantic instead of dataclasses?

The generated classes use the standard library dataclasses module, but the field names and types can be copied directly into a Pydantic BaseModel with minimal changes.

JSON to Python

Name: JSON to Python
Availability: InStock
Author: Nham Vu

Paste JSON and get typed Python dataclass definitions, including nested dataclasses for nested objects and arrays.

JSON Input

Options

Wrap every field in Optional[...] Root class name:

Python Dataclasses

Summary

Paste JSON and get typed Python dataclass definitions, including nested dataclasses for nested objects and arrays.

How it works

Paste a JSON object or array into the input box.
The parser walks the structure and infers a Python type for every field.
Nested objects are extracted into their own named dataclasses.
Arrays are typed as List[...] using the type of their elements.
The generated dataclass code appears in the output box, ready to copy.

Use cases

Turn an API response sample into typed Python models.
Bootstrap dataclasses for a script that consumes a JSON config file.
Generate a starting point for Pydantic-style models before adding validation.
Document the shape of a JSON payload as readable Python types.
Speed up writing test fixtures that mirror real JSON data.
Convert JSON from a webhook payload into structured Python objects.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu