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Free JSON to TypeScript / Zod / JSON Schema
A free, private JSON to TypeScript converter that runs entirely in your browser. Paste any JSON object or array and instantly generate strongly typed TypeScript interfaces, runtime-validating Zod schemas, or a standards-compliant JSON Schema. It is powered by quicktype, the open-source engine that generates strongly typed models and serializers from JSON, JSON Schema, TypeScript, and GraphQL queries, and the same quicktype-core library used in editors, CLIs, and production build pipelines runs right here on this page. quicktype infers the type of every field from your sample data, including nested objects, arrays, optional and nullable properties, unions, and enums, then renders clean, idiomatic output you can paste straight into your codebase. Choose a root type name, switch between TypeScript, TypeScript plus Zod, and JSON Schema targets, validate your JSON with friendly inline errors, and copy or download the result in one click. No JSON is uploaded, no account is required, and nothing is logged: the parsing and code generation both happen on your device.
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Convert JSON to TypeScript types without leaving the browser, powered by quicktype
This converter turns any JSON payload into strongly typed code right inside your browser. It is built on quicktype by glideapps, an open-source engine that generates strongly typed models and serializers from JSON, JSON Schema, TypeScript, and GraphQL queries. quicktype reads your sample data, infers the type of every field, and renders clean output, so there is nothing to install and no account to create: paste your JSON, choose a target, and get types.
Under the hood the page uses quicktype-core, the same npm package quicktype exposes for programmatic use in Node.js and the browser. That means the inference you get here matches what you would get from the quicktype CLI or from wiring quicktype into your own build, with the convenience of a paste-and-copy interface and zero setup.
TypeScript interfaces, Zod schemas, and JSON Schema from one sample
Pick TypeScript to get compile-time interfaces and type aliases that describe your data exactly. Pick TypeScript + Zod (the quicktype typescript-zod target) to generate Zod schemas that validate your data at runtime as well as type it, which is the safest way to handle untrusted API responses, form payloads, and config. Pick JSON Schema (the quicktype schema target) to produce a language-agnostic contract you can use for documentation, validation, or to generate types in other languages later.
quicktype infers nested objects as their own named types, types arrays by their element shape, and represents optional, nullable, and mixed-type fields as optional properties and unions. For the most accurate result, paste a representative array of records that includes every variant of your data rather than a single example, then set the root type name so the top-level type reads naturally in your codebase.
Private by design: your JSON never leaves your browser
Unlike many online converters that send your JSON to a server, this tool parses and converts everything locally using the open-source quicktype-core library, which is released under the Apache License 2.0. The JSON you paste never leaves your device, and no generated code is logged or stored remotely. You can verify this at any time by opening the Network tab in your browser DevTools while converting and watching that no JSON is sent.
That makes it safe for modeling sensitive payloads such as internal API responses, authentication tokens, or proprietary data structures. When the conversion succeeds, the result is one click from your clipboard or a downloaded file with the right extension, and when your JSON is malformed you get a clear, inline error pointing you at the problem rather than a silent failure.
How It Works
Paste or type your JSON into the editor: a single object, an array of objects, or a deeply nested document.
Pick an output target (TypeScript, TypeScript + Zod, or JSON Schema) and set a root type name.
quicktype infers the types locally and renders the code, ready to copy to your clipboard or download as a file.
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Key Features
Privacy & Trust
Use Cases
Limitations
- Types are inferred from the sample you paste: if your JSON omits a field, marks something null, or only shows one variant of a union, the generated types reflect only what was seen
- A single example cannot capture every optional or polymorphic case, so paste a representative array of records for the most accurate inference
- This page focuses on the TypeScript, Zod, and JSON Schema targets in just-types mode; quicktype supports many more languages and serializer options through its CLI and full API
- Generated output is a strong starting point, not a guarantee: review names, optionality, and unions before committing the types to your codebase
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Frequently Asked Questions
Is this JSON to TypeScript converter free?
Yes, it is completely free with no usage limits. You can convert as much JSON as you like into TypeScript interfaces, Zod schemas, or JSON Schema without paying, signing up, or installing anything. It is built on quicktype, an open-source project released under the Apache License 2.0, so both this tool and the underlying type-generation engine are free to use and free to inspect.
Is my JSON sent to a server?
No. The JSON you paste is parsed and converted to types entirely on your device, inside the browser, using the quicktype-core JavaScript engine. Nothing is uploaded, stored remotely, or logged. You can confirm this yourself by opening the Network tab in your browser DevTools while converting: you will see no request carrying your JSON data.
Do I need to install anything or run a CLI?
No. There is nothing to install. The converter is a single web page that loads the quicktype-core library and runs in any modern browser. If you prefer, the same quicktype engine is also available as a command-line tool and an npm package for build pipelines, but you do not need either to use this page. Just paste your JSON and pick a target.
What is the difference between the TypeScript, Zod, and JSON Schema outputs?
TypeScript output gives you compile-time interfaces and type aliases that describe the shape of your data. The TypeScript + Zod output (quicktype lang typescript-zod) generates Zod schemas that both type your data and validate it at runtime, which is ideal for checking untrusted API responses. JSON Schema output produces a language-agnostic, standards-compliant schema you can use for documentation, validation, or generating types in other languages.
Why are some fields marked optional or typed as a union?
quicktype infers types from the actual sample you provide. If a field is missing from some records in an array, it becomes optional. If a field holds different types across records, or contains null, it becomes a union or nullable type. To get the most accurate result, paste a representative array of records that includes every variant rather than a single example.
Does it handle nested objects and arrays?
Yes. quicktype walks the entire JSON tree, so nested objects become their own named interfaces or schemas, and arrays are typed by their element shape. Mixed-type arrays and deeply nested structures are inferred too. You can name the top-level type with the root type-name field, and nested types are named automatically from their keys.
Does it work offline and on mobile?
The conversion itself runs locally in your browser, so once the page and the quicktype-core library have loaded, the type generation does not need any further network access. You do need a connection for that initial load. The layout is responsive, so it works on phones and tablets as well as desktops, though pasting and reading code is most comfortable on a larger screen.