How are types mapped?

Strings become string, all numbers become number, booleans become boolean, and arrays become type[] based on their first element. Nested objects each get their own @typedef and are referenced by name.

What about null or empty arrays?

Their type can't be inferred from the sample, so null maps to * (any) and an empty array maps to *[]. Tighten these by hand if you know the real type.

Why JSDoc instead of TypeScript?

JSDoc @typedef lets you document and type-check plain JavaScript (for example with VS Code or tsc --checkJs) without adding a build step or .ts files.

Is my JSON sent anywhere?

No. Conversion happens entirely in your browser; nothing is uploaded.

JSON to JSDoc @typedef Generator

Developer

Paste any JSON object or array and get ready-to-use JSDoc @typedef definitions, with each field mapped to a JSDoc type (string, number, boolean, type[]) and separate @typedef blocks for nested objects. Perfect for adding types to plain JavaScript without TypeScript. null and empty arrays become the * (any) type. Everything runs locally in your browser — your JSON is never uploaded.

—

Root typedef nameJSON input

JSDoc typedefs

/**
 * @typedef {Object} Root
 * @property {string} name
 * @property {number} age
 * @property {boolean} active
 * @property {string[]} tags
 * @property {Meta} meta
 */

/**
 * @typedef {Object} Meta
 * @property {string} id
 */

How to use

Paste or type your JSON into the input box.
Optionally rename the root typedef (defaults to Root).
Copy the generated @typedef blocks into your JavaScript source.

Frequently asked questions

How are types mapped?: Strings become string, all numbers become number, booleans become boolean, and arrays become type[] based on their first element. Nested objects each get their own @typedef and are referenced by name.
What about null or empty arrays?: Their type can't be inferred from the sample, so null maps to * (any) and an empty array maps to *[]. Tighten these by hand if you know the real type.
Why JSDoc instead of TypeScript?: JSDoc @typedef lets you document and type-check plain JavaScript (for example with VS Code or tsc --checkJs) without adding a build step or .ts files.
Is my JSON sent anywhere?: No. Conversion happens entirely in your browser; nothing is uploaded.

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