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Type helper

JSON to TypeScript types

Paste any JSON and instantly generate a TypeScript type definition.
Objects and arrays are inspected to infer field names and nested shapes,
so you can drop the output straight into your codebase.

Nothing is sent to a server—parsing and type generation run entirely in your browser.

Guide: How to use & features

  • Paste JSON into the input and click “Convert to TypeScript.”
  • Objects are formatted into a structured block with typed properties.
  • Arrays are analyzed to determine element types; mixed content becomes a union.
  • Use the copy or clear buttons to reuse the output or start over.

Samples: Sample input & output

Generate TypeScript types

Input

{"title":"Draft","tags":["dev","web"],"stats":{"views":1200}}

Output

type Root = {
    title: string;
    tags: string[];
    stats: {
        views: number;
    };
};

FAQ: Frequently asked questions

  • Do you output interfaces or type aliases?

    The tool outputs TypeScript interfaces by default, deriving property names and types from the JSON structure.

  • Are arrays and nested objects supported?

    Yes. Array element types are inferred, and nested objects are composed recursively into the generated types.

  • How are optional properties decided?

    If a field is missing in parts of the sample, it is treated as optional. You can fine-tune the output afterwards as needed.

Use cases: Common use cases

  • Bootstrapping type definitions

    Generate TypeScript interfaces from sample backend responses to kick off a type-safe implementation quickly.

  • Aligning contracts

    Turn shared JSON into types to clarify expectations about field names, optional flags, and shapes.

  • Lightweight review snippets

    Produce minimal interfaces you can paste into PR comments to focus discussion on structure over typos.

Notes: Notes & limitations

  • Work stays in your browser

    Inputs and outputs remain local. Closing the tab or clearing cache will remove any temporary state.

  • Validate critical data

    Results are helper outputs—double-check them before sending to production systems or sharing externally.

  • Large payloads depend on your device

    Very large text or files can feel slow in some browsers. Use a desktop environment for heavy workloads.

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