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

• Next.js (App Router)
• json5 — relaxed JSON parsing
• jsonrepair — broken JSON repair
• Tailwind CSS v4

License

MIT