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JSON to TypeScript

Generate TypeScript classes/structs automatically from a JSON object.

100% Client-Side Local Execution
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What is JSON to TypeScript?

This free online tool turns a sample JSON payload into a ready-to-use interface or type alias for TypeScript, so you can use this json to typescript interface tool to go straight from raw JSON to a typed interface (or type alias) without writing the boilerplate yourself. It is built around TypeScript's actual idiom — a TypeScript interface — rather than a generic one-size-fits-all class, and pairs naturally with TypeScript's structural type system for real-world (de)serialization. Use it for json to typescript type or any time you need json to ts interface generator, whether you're scaffolding a new TypeScript project or mapping an existing API response.

Technical Execution

Paste or upload a sample JSON object or array and the tool walks its structure field by field, inferring a concrete TypeScript type for each value — mapping basic JSON types to `string`, `number`, and `boolean` as appropriate. For nested data, it emits a separate named interface for every nested JSON object, and types arrays as `T[]` (or `Array<T>`) of the matching element type. On the naming side, it preserves the original JSON key names exactly, since TypeScript interfaces describe object shapes directly rather than enforcing a renaming convention. For optional data, fields seen as `null`, or missing from some sample objects, are typed as `T | null` or marked optional with a `?` modifier (`field?: T`) depending on whether the key is ever actually absent versus merely null.

Zero Data Storage Guarantee

Everything runs client-side in your browser: the sample JSON you paste in — which may contain real field names, endpoint shapes, or structure from a private API or project — is parsed and converted entirely on your device and is never uploaded to any server. Nothing you enter is logged, stored, or transmitted anywhere, so you can safely paste a real payload from an internal or unreleased API to generate an accurate TypeScript interface. Closing or refreshing the tab clears everything, since no copy of your data ever left your machine in the first place.

How to Use JSON to TypeScript (Step-by-Step Guide)

  1. Copy a representative sample of your JSON (the more fields and nested objects it includes, the more complete the generated interface (or type alias) will be).
  2. Paste it into the input panel of the JSON to TypeScript tool, or click "Upload" to load it from a json file.
  3. Review the auto-detected root name, and rename it if you want the generated TypeScript interface to use a specific class or type name instead of the default.
  4. Click "Generate" to produce the TypeScript interface (or type alias), which appears instantly in the output panel with syntax highlighting.
  5. Click "Copy" to copy the generated code to your clipboard, or "Download" to save it as a `.ts` file.
  6. Paste the result into your TypeScript project and adjust field names or types if your data has edge cases the sample didn't cover.

Frequently Asked Questions (FAQ)

Q: How does this tool handle nested objects and arrays when converting JSON to TypeScript?
A: The tool emits a separate named interface for every nested JSON object, and types arrays as `T[]` (or `Array<T>`) of the matching element type That keeps the generated code organized the way a TypeScript developer would structure it by hand, instead of flattening everything into one giant interface (or type alias).
Q: What happens to fields that are nullable or missing from some records?
A: For optional data, fields seen as `null`, or missing from some sample objects, are typed as `T | null` or marked optional with a `?` modifier (`field?: T`) depending on whether the key is ever actually absent versus merely null. If your sample only has one example object, fields that could be null in other records might not be detected as optional — paste a few varied samples (or an array of objects) for the most accurate result.
Q: Is this better than writing the interface (or type alias) by hand?
A: For anything beyond a trivial, flat payload, yes — writing TypeScript interfaces by hand for a large nested API response is tedious and error-prone, and a missed optional field only surfaces later as a runtime type error that `tsc` never caught. The generator produces the same result in seconds and gives you a correct starting point to refine, rather than a blank page.
Q: Is my JSON data safe to paste into this tool, especially if it's from a private API?
A: Yes. Everything runs client-side in your browser: the sample JSON you paste in — which may contain real field names, endpoint shapes, or structure from a private API or project — is parsed and converted entirely on your device and is never uploaded to any server. Nothing you enter is logged, stored, or transmitted anywhere, so you can safely paste a real payload from an internal or unreleased API to generate an accurate TypeScript interface. Closing or refreshing the tab clears everything, since no copy of your data ever left your machine in the first place.
Q: Can I use this as a json to typescript interface online?
A: Yes — the tool is commonly used as a json to typescript interface online, and works the same way whether you're converting a one-off response for a prototype or generating model code for a production project.
Q: Does the tool rename fields to match TypeScript naming conventions?
A: Yes. It preserves the original JSON key names exactly, since TypeScript interfaces describe object shapes directly rather than enforcing a renaming convention, so the generated code reads naturally in TypeScript while still deserializing the original JSON correctly.
Q: What TypeScript library does the generated code work with?
A: The output is written to pair cleanly with TypeScript's structural type system, the most common choice for TypeScript developers handling JSON, so you can drop it into an existing project without changing your serialization setup.
Q: Does this tool work for deeply nested or large JSON samples?
A: Yes. The tool recurses through every level of nesting it finds and generates a complete set of linked interface (or type alias) definitions, not just the top level — though for very large samples, trimming it down to one representative record per array is usually enough to get an accurate result.
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