jsonguy

JSON formatter, validator, and repair tool. Accepts JSON5, JavaScript objects, and Python dicts (single quotes, None/True/False, tuples).

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Documentation

JSONGuy

A modern online JSON formatter, validator, beautifier, and repair tool. It accepts the syntax people actually use — JSON5, JavaScript objects, and Python dicts — and normalizes everything into strict, standards-compliant JSON. Runs 100% in the browser.

Live at jsonguy.airankone.com.

Features

  • Formatter & beautifier with 2/4-space indent and GitHub-style syntax highlighting
  • Validator that reports the exact line and column of an error
  • Collapsible tree view for navigating nested data
  • JSON repair — fixes missing quotes, missing commas, and unclosed brackets
  • Python dict support — single quotes, None/True/False, and tuples are normalized to JSON
  • JSON5 support — unquoted keys, comments, and trailing commas
  • Client-side only — your data never leaves the browser

MCP Server

Format, validate, and repair JSON from any MCP client (Claude Desktop, Cursor, Cline, etc.).

  • Endpoint: https://jsonguy.airankone.com/mcp
  • Transport: Streamable HTTP (JSON-RPC over POST, no API key)
  • Tools:
    • format_json — format JSON / JSON5 / JS objects / Python dicts into strict JSON
    • validate_json — validate input and return the error line/column when invalid
    • repair_json — repair broken JSON

Connect

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "jsonguy": {
      "type": "http",
      "url": "https://jsonguy.airankone.com/mcp"
    }
  }
}

Development

npm install
npm run dev

Open http://localhost:3000.

npm run build   # production build
npm run lint    # eslint
npm run indexnow # submit URLs to IndexNow (Bing/Yandex/Naver)

Tech