JSON to TypeScript Converter — Generate TypeScript Interfaces from JSON

JSON to TypeScript Converter — Generate TypeScript Interfaces from JSON. Free online JSON to TypeScript converter.

Paste any JSON object to instantly generate TypeScript interfaces with correct type inference — all processed in your browser with no data uploaded. Instantly convert JSON to TypeScript with our free online JSON to TypeScript converter.

Paste any JSON object and get clean, correctly typed TypeScript interfaces with automatic type inference for strings, numbers, booleans, arrays, and nested objects — perfect for typing API responses, defining Redux state shapes, and accelerating frontend development.

Whether you are a React developer building component props, an Angular engineer structuring service models, or a Node.js developer defining request/response types, our tool makes it easy to generate TypeScript interfaces from JSON in seconds.

Our JSON to TypeScript tool supports nested objects (generating sub-interfaces automatically), arrays, and all JSON primitive types. It runs entirely in your browser — your API keys, response data, and business models never leave your device.

Try our JSON Schema Generator to generate JSON Schema instead, JSON to TOML for config format conversions, or JSON Prettify to format your JSON before generating interfaces.

Frequently asked questions

How do I generate TypeScript interfaces from JSON?

Paste a JSON object or array into JSON Input. The TypeScript Interfaces panel shows an exported interface for the root and one for every nested object; click Copy Interface to copy all of them.

How do I change the interface names?

Type a name in Interface Root Name, for example User. The root interface uses that name, and nested objects get interfaces named after their key in PascalCase, so a key called billing_address becomes BillingAddress. A name that is already taken gets a number, such as User2, and a key starting with a digit gets an Item prefix, so 123 becomes Item123.

How are arrays and null values typed?

Arrays of one primitive type become types like string[], and mixed primitives become a union array. Objects in an array share one interface built from the first object, combined into a union with any primitives next to them, and nested arrays of objects become types like Item[][]. Empty arrays become unknown[] and null values are typed as null.

Are optional properties detected?

No. Every key in your sample becomes a required property, and only the first object of an array is inspected. Add a question mark to properties that can be missing after you copy the code.

Why is the output empty?

The input must be strict JSON. Comments, trailing commas or single quotes make it invalid, Invalid JSON appears next to the JSON Input label and no interfaces are generated.

How to use this online tool

JSON to TypeScript Converter — Generate TypeScript Interfaces from JSON is designed for fast browser workflows when you need to format, validate, convert, decode, encode, generate, or inspect data without opening a heavy desktop app. Start with the input field or visible options, review the result, then copy or download the output for the next step.

Private processing in your browser

JSON to TypeScript Converter — Generate TypeScript Interfaces from JSON keeps the normal processing step local in your browser. That is useful for code snippets, tokens, documents, configuration values, text samples, and other material that should not be sent to a remote service unless you explicitly choose to share it.

When this tool is useful

Use JSON to TypeScript Converter — Generate TypeScript Interfaces from JSON for repeatable developer tasks, technical documentation, QA checks, quick conversions, debugging, content cleanup, and internal team workflows. The page focuses on clear inputs, immediate feedback, and output that is easy to reuse in code, reports, tickets, emails, or notes.

Practical tips

Before copying the final result, check important details such as spacing, casing, filenames, encoding, token structure, line breaks, or output format. Small checks prevent mistakes when the result is reused in source code, API requests, documentation, spreadsheets, or shared files.