JSON to TypeScript Converter
Generate TypeScript interfaces and types from any JSON structure instantly. Powered by AI for intelligent naming, JSDoc annotations, and optional field detection.
How It Works
Paste Your JSON
Paste a JSON object or array into the input editor. Supports API responses, config files, and any valid JSON structure.
Configure Options
Choose interface or type alias, toggle export and readonly, set your root type name, and select AI or local generation.
Copy Your Types
Copy the generated TypeScript interfaces or download as a .ts file. Ready to drop into your project.
Why Generate Types from JSON
Type-Safe API Responses
Generate interfaces that match your API payloads, catching shape mismatches at compile time.
API Contract Documentation
Turn JSON responses into typed contracts that serve as living documentation for your endpoints.
Faster Development
Skip writing interfaces by hand. Paste JSON, get types instantly, and stay in your flow.
Catch Shape Mismatches
Detect missing fields, wrong types, and nullable values before they cause runtime errors.
Supported Features
FAQ
How does it handle nested objects?
Each nested object gets its own named interface, derived from the JSON key name. For example, an "address" field becomes an Address interface. The AI mode generates even more meaningful names based on data context.
What happens with arrays?
Arrays are analyzed to determine element types. If all elements share the same shape, a single typed array is generated. Mixed-type arrays produce union types. Empty arrays are typed as unknown[].
How are null values handled?
Null values are typed as union types (e.g., unknown | null) since the actual type cannot be inferred from null alone. The AI mode can often infer the intended type from field naming patterns.
What does the AI mode add?
AI mode generates semantically meaningful interface names (e.g., "User" instead of "Root"), adds JSDoc comments for dates, emails, and IDs, and can intelligently mark fields as optional based on common patterns.
Is this tool free?
Yes, completely free with no signup required. Both local (AST) and AI-powered generation are available at no cost.
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