JSON to Code

Generate TypeScript, C# or Java classes from sample JSON

100% free. Runs entirely in your browser - your files and data never leave your device and nothing is uploaded to any server.

Sample JSON

export interface Root {
  id: number;
  name: string;
  isActive: boolean;
  tags: string[];
  address: Address;
  projects: Projects[];
}

export interface Address {
  city: string;
  zip: string;
}

export interface Projects {
  title: string;
  year: number;
}

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About this tool

Generate ready-to-use class/model definitions - in TypeScript, C#, or Java - directly from a sample piece of JSON data, inferring field names and types automatically. It saves the tedious, error-prone work of manually writing out a matching class definition every time you need to consume a new API response shape.

How to use this tool

  1. Paste sample JSONProvide a realistic API payload with representative fields and nested objects.
  2. Choose target languageSelect TypeScript, C#, or Java based on your project stack.
  3. Generate modelsCreate inferred classes/interfaces with types mapped from JSON values.
  4. Review and refineAdjust naming, nullability, and optional fields to match project conventions.

Key features

  • Saves time on repetitive model/class boilerplate writing.
  • Reduces manual typing mistakes in nested object structures.
  • Supports common backend and frontend language targets.
  • Useful starting point for API integration workflows.

Common uses

  • Bootstrapping DTOs from new API responses.
  • Generating initial models for mobile/web app clients.
  • Speeding up prototyping when API schema changes frequently.
  • Teaching juniors how payload shape maps to typed code.

Tips for better results

  • Use multiple payload samples to catch optional and nullable variants.
  • Rename generated symbols to match your codebase style guide.
  • Validate number vs string assumptions for IDs and timestamps.
  • Keep generated code under version control for easy diff review.

Mistakes to avoid

  • Generating models from an incomplete sample and assuming full schema coverage.
  • Skipping nullability review for fields that vary across endpoints.
  • Trusting inferred types blindly without backend contract validation.
  • Mixing generated naming conventions with existing project patterns.

Frequently asked questions

Types are inferred from the values present in your sample JSON, so they're accurate to that specific example - fields that could be null, optional, or have different types in other API responses won't be reflected unless your sample includes those variations.

TypeScript, C#, and Java class/interface definitions are supported, covering common backend and frontend use cases.

Yes - it's meant as a working starting point; review naming conventions and nullability to match your project's specific style before relying on it long-term.

Yes. JSON To Code is free for normal use with no account required, and ToolBox does not add a watermark to your result.

Most tools in this category run in your browser so the file stays on your device. If a tool needs a temporary server job, files are handled for that job only and are not kept as a lasting archive.

No install needed. Open JSON To Code in your browser, add your file or paste your input, then download or copy the result.

Yes on modern mobile browsers. For large files, a desktop browser is usually faster and more reliable.

Try a different quality or format setting, use a smaller input, or open a related tool (for example compress before convert). Keep a copy of the original file before replacing it.

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