JSON to TypeScript Converter
Generate typed interfaces and type aliases from any JSON structure.
Naming convention
Array syntax
Ready
TypeScript will appear here
Paste or load a sample to begin
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JSON to TypeScript Converter – Interfaces & Types
Free JSON to TypeScript Converter: paste JSON and get TypeScript interfaces or type aliases instantly. Handles nested objects, unions and optional fields.
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What is JSON to TypeScript Converter?
JSON to TypeScript Converter turns pasted JSON into strongly-typed TypeScript interfaces or type aliases, the same kind of output tools like quicktype generate, without installing anything. It handles nested objects, arrays, optional and nullable fields, union types for mixed-value arrays, interface deduplication and root-array aliases. Configure naming convention, array syntax, export keyword and semicolons, then download a .ts file. All processing is 100% browser-side, so your data never leaves your device.
- json
- typescript
- interface
- type generator
- converter
Features
What you get with JSON to TypeScript Converter.
Deep Nesting
Recurses through any object depth, generating a named interface for every nested object.
Union & Optional Types
Mixed-type arrays produce (string | number)[] unions; toggle optional (?) fields with one switch.
Interface Deduplication
Structurally identical objects reuse the same interface instead of creating redundant copies.
Root Array Support
Top-level JSON arrays generate both the item interface and a typed list alias automatically.
Configurable Output
Choose PascalCase or camelCase, T[] or Array<T>, export keyword, and semicolon style.
Download as .ts
Export the generated interfaces directly as a .ts file — ready to drop into any project.
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Frequently asked questions
Common questions about JSON to TypeScript Converter.
Yes — the converter recurses through any depth and produces a separate named interface for each nested object level.
Enable the 'Optional fields' toggle to mark all fields with ? (field?: Type). This is useful when your JSON samples may be incomplete.
Arrays containing different value types are automatically typed as union arrays, e.g. (string | number)[]. Empty arrays become unknown[].
Yes — the tool unwraps the first object in the array to build the item interface, then adds an export type RootList = Root[] alias at the end.
No — all conversion logic runs entirely in your browser using JavaScript. Nothing is transmitted or stored.
Copy the interfaces or click 'Download .ts' to save a file. Import the interfaces into your TypeScript files as you would any .d.ts or .ts module.
Quicktype is a feature-rich CLI and library supporting many output languages. This tool is a focused, browser-only JSON-to-TypeScript converter with no install — paste JSON, get interfaces, and configure naming and syntax directly in the UI.
Yes. Choose TypeScript interfaces or type aliases for the output, and the converter generates either from the same JSON. Identical nested shapes are deduplicated so you do not end up with repeated interfaces.
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