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JSON to TypeScript – Generate Interfaces Online
Convert any JSON object to TypeScript interfaces instantly. Handles nested objects, arrays, optional fields, null values, and union types automatically. Download as a .ts file.
JSON to TypeScript Converter
Generate typed interfaces from any JSON structure
TypeScript output will appear here
Paste JSON on the left to generate interfaces
How conversion works
Type inference
string, number, boolean, null, arrays, and nested objects are all inferred automatically.
Deduplication
Structurally identical nested objects reuse the same interface name instead of duplicating.
Union arrays
Mixed-type arrays produce union types like (string | number)[] automatically.
Deep nesting
Arbitrarily deep object trees are fully traversed and all types are extracted.
Root arrays
Top-level JSON arrays generate a typed list alias alongside the item interface.
Options
Control naming convention, array syntax, optional fields, export keyword, and semicolons.
All conversion runs locally in your browser — no data is sent to any server.
What is JSON to TypeScript Converter?
Paste JSON and instantly receive strongly-typed TypeScript interfaces. Automatically 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. Download output as a .ts file — all processing is 100% browser-side.
JSON to TypeScript Converter Features
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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JSON to TypeScript Converter FAQ
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.