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JSON → TypeScript

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Paste any JSON object and get accurate TypeScript interface definitions in one click. including nested types.

JSON Input
Generated TypeScript
Ctrl+Enter Generate

Generate TypeScript Interfaces from JSON

Paste any JSON object and instantly get accurate TypeScript interfaces and type definitions. The generator handles nested objects, typed arrays, union types, and optional fields so you never have to write boilerplate types by hand again. 100% private, runs entirely in your browser.

Use Cases

API Response Typing
Copy a real API response, paste it here, and get production-ready interfaces in seconds. Validate the JSON is well-formed first with the JSON Formatter, then generate types for your frontend or backend client.
Preventing Runtime Errors
Strong typing catches shape mismatches at compile time. After generating interfaces, generate a validation schema with the JSON Schema Generator to enforce the same contract at runtime.
Onboarding New APIs
When integrating a third-party API for the first time, generate types from the sample response in the docs. Compare responses across API versions with the JSON Diff tool to spot breaking changes before updating your types.
Cleaner Code Contracts
Explicit interfaces improve IDE autocomplete and code reviews. Clean null-heavy API responses first with JSON Cleaner to generate tighter, non-nullable interfaces.

How to Use

  1. Paste your JSON object into the input panel
  2. Set a root interface name in the toolbar (default: Root)
  3. Click Generate or press Ctrl+Enter to produce TypeScript interfaces
  4. Copy the output or download it as a .ts file

Features

  • Generates named interfaces for every nested object in your JSON
  • Infers string, number, boolean, null, and typed arrays
  • Union types for heterogeneous arrays like (string | number)[]
  • Customizable root interface name
  • Download output as a .ts file
  • 100% private: no server, no upload, no data leaves your browser

Frequently Asked Questions

What TypeScript output does this produce?

The tool generates TypeScript interface declarations for every object in your JSON. Primitive values map to string, number, boolean, or null. Arrays become typed arrays, and mixed-type arrays produce union types like (string | number)[]. Nested objects each get their own named interface.

Does it handle nested objects?

Yes. Every nested object generates its own named interface. The parent interface references the child interface by name, mirroring the actual JSON hierarchy so your TypeScript code stays readable and well-organized.

Can I use this for API response types?

Absolutely. Paste a real API response directly into the tool and get ready-to-use TypeScript interfaces in seconds. This is one of the most common workflows: fetch an endpoint, copy the response JSON, and generate types without writing them by hand.

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