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JSON to TypeScript, Go & Java Converter

Paste JSON and get export-ready TypeScript interfaces, Go structs, or Java POJOs with automatic type inference — nested objects, arrays, unions, and optional fields. Runs entirely in the browser.

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CONFIG
Optional fields get ?, nulls become the null type.
JSON INPUT
Everything runs locally in your browser — your JSON never leaves the page. Cleaning up data first? Try the JSON Formatter, check structure against a schema with the JSON Schema Validator, or move it to a spreadsheet with the JSON to CSV Converter.

Why JSON to TypeScript Converter?

The fastest way to break a build is an API response that does not match the types you assumed. This converter pastes a real payload and writes the interfaces for it - nested objects, arrays, unions, and optional fields included - so the type definitions always describe the data that actually comes back, instead of the one you guessed at.

  • Paste a representative response from the API docs, not the smallest one - the more shapes you include, the more accurate the optional and union types.
  • Keys missing from some objects in an array come out as optional, so sparse records stay typed without lying about the data.
  • The output is export-ready: drop the .ts file into a types folder and import the root type in your client.
  • Pair it with the JSON Formatter when a payload is malformed, and the JSON Schema Validator when you need runtime checks on top of the types.

What is JSON to TypeScript Converter?

JSON to TypeScript, Go & Java Converter turns a JSON document into export-ready type declarations in three languages. It infers the shape automatically: primitives become string/number/boolean (int64/float64 in Go, Integer/Double in Java), nested objects become their own interfaces, structs, or nested POJO classes, arrays become typed arrays or List<> (with unions when elements vary), nulls become null, interface{}, or Object, and keys that appear only on some objects in an array are marked optional (TS ?, Go ,omitempty). Keys that are not valid identifiers are quoted in TypeScript, kept in the json tag in Go, and renamed with a Jackson @JsonProperty annotation in Java so the output works as-is. Everything runs in the browser.

Common Use Cases

API Client Typings

Paste a sample API response and generate the TypeScript types for your client, fetch handlers, or React Query hooks in seconds — or the Go structs and Java POJOs for your backend integration.

Test Fixture Types

Type the JSON fixtures used in unit tests and seed data so mismatches between fixtures and code fail at compile time, in any of the three languages.

Legacy Data Migration

Generate types, structs, or POJOs for undocumented JSON exports, config dumps, or third-party payloads you are onboarding into a typed codebase.

Schema Exploration

Understand the shape of an unfamiliar payload — the generated declarations are a readable map of every field and its type.

How to Use This Tool

  1. Paste a JSON document into the input area (or load the sample to see the output shape)
  2. Pick the target language — TypeScript, Go, or Java (and a root type name)
  3. Click Convert — nested objects get their own types, arrays get typed elements, optional keys are marked
  4. Copy the code or download it as a .ts, .go, or .java file and drop it straight into your project

Related Tools

JSON Formatter → JSON Schema Validator → JSON to CSV Converter → JSON to YAML Converter → cURL to Code Converter → HTTP API Tester →

Learn More

JSON to TypeScript Converter is a free online tool that requires no signup or installation. It works directly in your browser, keeping your data private and secure.