JSON to TypeScript
Generate strongly typed TypeScript interfaces and type declarations from raw JSON payloads with automatic nested object inference and union type extraction.
Infers complex array unions, nested schemas, and optional fields securely on client side.
Zero-Config Type Inference
Paste any JSON payload to immediately output production-ready TypeScript declarations.
Automated TypeScript Interface & Type Generation
Writing manual TypeScript type definitions for complex REST and GraphQL API responses is tedious and error-prone. One missed optional field or mismatched nested object can cause subtle runtime type issues.
The JSON to TypeScript generator automatically infers nested structures, detects array item unions, and outputs production-ready TypeScript interfaces or type aliases with optional/readonly modifiers.
Core Tool Capabilities
- Deep Nested Type Inference: Recursively analyzes nested objects and extracts clean, modular type interfaces.
- Array Union Extraction: Infers polymorphic array item types and generates precise union declarations.
- Configurable Declaration Style: Choose between interface and type alias declarations with optional export keywords.
- Modifier Support: Toggle optional (?) and readonly modifiers across all generated properties.
Local Browser Privacy
Your files are processed locally on your device. Files are not uploaded, transmitted, or stored on remote servers.
Once the page has loaded, you can disconnect your network connection and continue using this tool offline.
Target Use Cases
- • Typing REST API Responses
- • Database & Config Schemas
- • Frontend State Modeling
- • API Documentation
Technical Specifications & Platform Limits
Supports deep nested structures and primitive arrays
Customizable root naming and export statements
Zero external network requests or logging
Valid standard TypeScript definitions
Step-by-Step Workflow
Paste JSON Payload
Paste your API response or JSON object into the left input panel.
Configure Type Options
Specify the root interface name, declaration style, and property modifiers.
Inspect Inferred Types
Review generated TypeScript definitions with syntax highlighting on the right.
Copy & Use
Click Copy TS to paste the definitions directly into your codebase.
Practical Real-World Use Cases
Typing REST API Responses
Convert JSON payloads from external endpoints into strict TypeScript types.
Database & Config Schemas
Generate type definitions for JSON configuration files and database exports.
Frontend State Modeling
Quickly define Redux, Zustand, or React state interfaces from mock data.
API Documentation
Create clear schema models for internal developer docs and technical specs.
Frequently Asked Questions
- How does the generator handle heterogeneous arrays?
- When array items contain different primitive types or object schemas, the generator produces union array types like (string | number)[].
- Can I choose between interface and type declarations?
- Yes. Use the declaration style toggle to switch between TypeScript interfaces and type aliases.
- Are null and undefined values supported?
- Yes. Null values are typed as unknown and can be marked as optional properties.
- Is my JSON data kept private?
- Yes. All parsing and type generation executes entirely in your browser without communicating with any backend.
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