JSON to TypeScript Converter
Convert JSON payloads into clean, idiomatic TypeScript interfaces or type aliases instantly in your browser.
How the JSON to TypeScript Converter Works
The JSON to TypeScript Converter analyzes raw JSON data and automatically infers type definitions, allowing developers to safely type API responses, configuration objects, and local mock payloads.
Type Inference Rules
- Primitives: Strings, numbers, and booleans map directly to
string,number, andboolean. - Nested Objects: Converted into separate PascalCase interfaces or types to promote clean, reusable code structures.
- Heterogeneous Arrays: Array items with differing primitive types are represented as union arrays, such as
(string | number)[]. - Array of Objects: Object elements in arrays are merged into a unified item interface, with non-universal properties automatically marked as optional.
- Special Key Characters: Keys containing hyphens, spaces, or non-alphanumeric characters are safely wrapped in quotes.
Customization Options
- Root Name: Choose a custom root type identifier to match your project naming conventions.
- Interface vs Type Alias: Toggle between TypeScript
interfacedeclarations andtypedefinitions. - Export Keyword: Toggle whether types should be prefixed with
export. - Readonly Properties: Optionally prefix all inferred properties with
readonlyfor immutable data pipelines.
Frequently Asked Questions
How does the converter handle nested objects?+
The tool automatically extracts nested objects into standalone, PascalCase-named sub-interfaces (or types) referenced by the parent structure.
How are arrays of objects converted?+
The engine scans objects within the array, merges all unique property keys, and marks missing or nullable properties as optional (`?`).
Can I customize the root interface name?+
Yes, you can type any custom identifier (such as `UserProfile` or `ApiResponse`) into the Root Name control in the top toolbar.
Is any JSON data sent to an external server?+
No, type inference and AST generation run entirely client-side in your browser JavaScript engine.