Generate TypeScript Types and JSON Schema from JSON

Tool Overview: JSON to TypeScript & JSON Schema Converter

Transform any JSON payload into strongly typed TypeScript definitions and a production-ready JSON Schema in one click. This tool keeps your API contracts, configuration files, and mock data synchronized across FE/BE stacks by sharing a single source of truth.

What Is JSON to TypeScript?

JSON to TypeScript converts the structure of a JSON payload into TypeScript interfaces/types and a JSON Schema. It reduces manual typing, keeps validators in sync, and gives teams a shared, reliable contract.

How to Use

1. Paste an API response, config JSON, or sample payload.
2. Set the root interface name, schema title, and indentation.
3. Generate TypeScript or Schema, then copy or download.

Common Use Cases

• Generate TypeScript types from API responses for better autocomplete.
• Produce JSON Schema for validation and form rules.
• Keep mock data, docs, and server validators aligned.

✨ Highlights

• 🧱 Bidirectional confidence – generate both interfaces and schemas from the exact same JSON so type systems, validators, and docs stay aligned.
• ⚙️ Configurable output – rename the root interface, pick the JSON indent you prefer, and download the results for your IDE or repo.
• 🧪 Robust inference – nested arrays, mixed unions, and nullable fields are detected automatically with optional properties handled in JSON Schema.
• 🌍 Multi-language UI – matches the existing ToolMi layout, supports /en/ & /zh/ routes, and inherits all accessibility helpers.

📋 Example

Sample JSON

{
  "project": "ToolMi",
  "version": "1.0.0",
  "features": [
    {
      "name": "Type generator",
      "status": "stable",
      "contributors": 8
    },
    {
      "name": "JSON schema",
      "status": "beta",
      "contributors": 5
    }
  ],
  "meta": {
    "updatedAt": "2024-03-12T08:45:00Z",
    "tags": ["json", "typescript", "schema"],
    "production": true
  }
}

Generated TypeScript

export interface RootObject {
  project: string;
  version: string;
  features: FeatureItem[];
  meta: Meta;
}

export interface FeatureItem {
  name: string;
  status: string;
  contributors: number;
}

export interface Meta {
  updatedAt: string;
  tags: string[];
  production: boolean;
}

Generated JSON Schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "JSON Schema",
  "type": "object",
  "additionalProperties": false,
  "required": ["project", "version", "features", "meta"],
  "properties": {
    "project": { "type": "string" },
    "version": { "type": "string" },
    "features": {
      "type": "array",
      "items": {
        "type": "object",
        "additionalProperties": false,
        "required": ["name", "status", "contributors"],
        "properties": {
          "name": { "type": "string" },
          "status": { "type": "string" },
          "contributors": { "type": "integer" }
        }
      }
    },
    "meta": {
      "type": "object",
      "additionalProperties": false,
      "required": ["updatedAt", "tags", "production"],
      "properties": {
        "updatedAt": { "type": "string" },
        "tags": {
          "type": "array",
          "items": { "type": "string" }
        },
        "production": { "type": "boolean" }
      }
    }
  }
}

🔧 Usage Tips

1. Clean the JSON first – remove trailing commas and comments so the parser can infer the real structure.
2. Name the root interface – RootObject works, but giving it a domain name (e.g., BillingSettingsResponse) makes IDE autocomplete clearer.
3. Validate against real responses – paste production API snapshots regularly; the JSON Schema highlights required vs optional drift instantly.
4. Download artifacts – keep the types.d.ts or schema.json output under version control to review diffs in pull requests.

❓ FAQ

Q1: JSON parsing failed. What should I check?
A: Make sure your JSON is valid (no comments, trailing commas, or invalid quotes).

Q2: Why are some fields optional?
A: The tool infers required fields from the sample. Paste a fuller response to improve accuracy.

Q3: Does it support nested arrays and unions?
A: Yes, nested arrays, mixed unions, and nullable fields are detected automatically.

Q4: Can I export the results?
A: Use the download buttons to save types.d.ts and schema.json for your project.