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JSON Toolbox- Free online JSON tools

JSON to TypeScript

Convert JSON to TypeScript interfaces online. Types are inferred for nested objects and arrays — and everything runs in your browser.

  • 100% client-side, nothing uploaded
  • Instant results
  • Works offline once loaded
Input JSON

Empty

TypeScript output

Empty

How it works

About this tool

This free online JSON to TypeScript generator turns a sample JSON payload into TypeScript interfaces. Paste a representative response, set a root type name, and the tool infers a type for every field — including nested objects and array elements.

Each field gets a precise type — string, number, boolean, arrays, and nested interfaces. Fields that are null or missing in some samples are marked optional or nullable, so the interfaces match real-world API responses.

Use it to scaffold types from an OpenAPI sample, a captured API response, or a fixture file before you hand-tune the result for your project’s conventions.

Generation runs entirely in your browser. Your JSON is never uploaded or stored, so it is safe to use with production API responses and payloads that contain sensitive data.

JSON Toolbox processes all data locally in the browser. Nothing is uploaded to a server.

Common questions

Frequently asked questions

How do I convert JSON to TypeScript?
Paste your JSON into the input editor and the generated TypeScript code appears on the right. Set a root type name to control what the top-level type is called, then copy or download the result.
Does it handle nested objects and arrays?
Yes. Nested objects become their own named types, and arrays are typed by their element. When objects in an array have slightly different shapes, their fields are merged and any field missing from some items is marked optional.
What should I know about the generated TypeScript code?
Inference is based on the sample you paste, not a formal schema. Unions of unrelated shapes may collapse into a broader type, and deeply dynamic maps may be typed more loosely than a hand-written definition. Treat the output as a strong starting point, then refine names and unions as needed.
Is my JSON uploaded anywhere?
No. The TypeScript code is generated locally in your browser. Nothing is sent to a server, logged, or stored — even for large or sensitive payloads.

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