Free Online JSON to TypeScript

The JSON-to-TypeScript converter inspects a JSON sample and emits matching TypeScript interface definitions, with nested objects becoming named child interfaces.

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How to Use This Developer Tool

  1. Paste your JSON sample into the input area.
  2. Optionally change the root interface name.
  3. Read the generated interfaces in the output panel.
  4. Click Copy to send the TypeScript to your clipboard.

What Is a JSON to TypeScript?

When you call a new API and want types for the response, hand-writing the interface from a sample is mechanical work. This converter does it automatically: each object becomes a named `interface`, each array's element type is inferred from its members, and primitive types map to TypeScript's `string`, `number`, `boolean`, and `null`.

The root interface uses the name you provide (defaulting to `Root`); nested object properties get child interface names derived from the property they appear under. Empty arrays default to `unknown[]` so you can fill in the right element type by hand. The output is ready to paste straight into a `.ts` file or a shared type-definitions package.

Frequently Asked Questions

How does JSON to TypeScript work?
The tool analyzes your JSON structure and generates matching TypeScript interfaces. Nested objects become nested interfaces and arrays get element types.
Can it handle null values?
Yes — keys with null values are typed as `null | T` once another sample provides T, otherwise they're typed as `null`.
What about array element types?
Arrays infer their element type. Empty arrays default to `unknown[]`. Mixed-type arrays produce a union element type.

Published by the WeGotEveryTool team. We build and test every tool in-house and update pages when the underlying spec, formula, or recommendation changes.

Reviewed: May 2026. Disclaimer: this tool is provided as-is for general informational use. For decisions with material consequences (medical, legal, financial, security) verify results against a qualified professional source.

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