JSON to TypeScript

TypeScript's type system relies on interfaces and type aliases to define the shape of data. When working with API responses, database records, or configuration files, manually writing TypeScript types for complex nested JSON structures is tedious and error-prone. The AllTools JSON to TypeScript converter automates this process — paste a JSON sample and get accurate TypeScript interfaces instantly. The converter analyzes the JSON structure recursively: objects become interfaces with typed properties, arrays become typed arrays with the element type inferred from content, nested objects generate separate named interfaces, and primitive values map to string, number, boolean, or null types. Union types are generated when array elements have inconsistent types. Optional properties (marked with ?) are detected when a key appears in some objects but not others within an array. The output follows TypeScript best practices: PascalCase interface names, readonly modifiers for immutable data, and proper nesting with exported interfaces. All code generation happens in the browser using pure string manipulation — your API response data, which may contain production values with sensitive information, never leaves your device.

TypeScript type generation from JSON is a fundamental step in type-safe API development workflows. When building frontend applications that consume REST or GraphQL APIs, having accurate TypeScript types for API responses enables IntelliSense autocompletion, compile-time error detection, and refactoring safety across the entire codebase. The typical workflow is: make an API request, capture the response JSON, generate TypeScript interfaces from the response, and use those interfaces to type your fetch calls, state management, and component props. For projects using OpenAPI/Swagger specifications, JSON Schema, or GraphQL, dedicated code generators exist — but for quick API integration, ad-hoc endpoint testing, or prototyping, generating types from a sample JSON response is faster and requires no build tooling. The AllTools converter produces types that work with both interface and type alias styles, and handles edge cases like null values, empty arrays (typed as unknown[]), and deeply nested structures. The generated types can be pasted directly into .ts or .d.ts files in your project.