TypeScript

JSON to TypeScript Converter

Convert JSON into TypeScript interface/type definitions.

Conversion Options

Select output style and rules.

Root type name

Null handling

Use type

Output type aliases instead of interfaces.

Generate enums

Convert repeated string literals into enums.

Input

Only valid JSON strings are supported. Adjust the root name and options.

Output

interface

What

JSON to TypeScript Converter definition

Analyze JSON strings in the browser and generate copy-ready TypeScript type definitions.

Cases

Use Cases

Generate types for API responses

Improve type safety in front-end models

Bootstrap types for documentation or SDKs

How To

How to Convert JSON to TypeScript

Generate reusable TypeScript types directly from JSON input.

Paste JSON

Paste a valid JSON object or array into the input.

Adjust options

Choose root name, null handling, and enum generation.

Generate and copy

Click generate to get TypeScript code and copy it.

Knowledge

Background Knowledge for JSON to TypeScript

What is TypeScript?

TypeScript is a superset of JavaScript released by Microsoft in 2012. It adds static types to improve safety, tooling, and refactoring in large codebases.

Why convert JSON to TypeScript?

JSON is runtime data, while TypeScript types are compile-time contracts. Converting clarifies API shapes and helps catch missing or mistyped fields early.

Ways to define types in TypeScript

Use interface for object shapes and declaration merging, and type for unions, intersections, and aliases. Pick based on the modeling need.

Structural typing

TypeScript is structurally typed, so compatibility is based on shape rather than name. This helps when comparing converted JSON types to existing models.

FAQ

JSON to TypeScript FAQ

What JSON can I use?

Any valid JSON object or array string works.

What if fields differ across objects in an array?

Field types are merged into unions and missing fields become optional.

How is null handled?

By default it is included in unions; you can switch to optional fields.

What about empty arrays?

They are emitted as unknown[].

When should I use enums?

When the same field repeats string literal values.

How are nested objects named?

Nested types are created as ParentField names in PascalCase.

Is any used?

No. Unknown is used instead of any.

Does it run in the browser only?

Yes. It relies on JSON parsing and runs in the browser.

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