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JSON Validator

Validate JSON syntax with detailed error messages. Powered by CapabilityBase Runtime.

💡 Why this exists

Before you pipe AI-generated JSON into your API, database, or config file, you need to know it's valid. A single trailing comma or unquoted key can crash your entire pipeline. This Capability tells you exactly what's wrong — instantly, deterministically, without calling an API.

⚖️ Need to validate JSON?

✅ CapabilityBase
  • Instant — ~0.005ms
  • Precise line-level error messages
  • Zero network calls
  • Free, no API key
Try it live →
💬 ChatGPT / Claude Reference only
  • ~500-2000ms per call
  • May miss subtle syntax errors
  • Requires API call + token cost
  • May "fix" JSON without asking
Result will appear here...

Capability Info

IDjson.validate
Version1.0.0
Statusstable
CategoryJSON
Contractdeterministic, no side effects, local, no AI
RuntimeBrowser, Node, Edge, Worker
Consumesjson
Producesvalidation

Related Tools

{ } JSON Formatter 🔧 JSON Repair 🔐 Base64 Encoder # Token Counter

AI is probabilistic. Your tools shouldn't be.

Frequently Asked Questions

What error messages does it provide?

Precise, position-aware messages: line, column, unexpected token, missing comma, unclosed brace — enough to fix the issue immediately.

Does it validate JSON5 or JSONC?

No — it enforces strict RFC 8259 JSON. For loose formats with comments/trailing commas, use the JSON Repair capability instead.

Can it be called programmatically?

Yes. The validation core is exposed as a deterministic capability (json.validate) usable via URL deep link for agents and scripts.

Tools we recommend

Deploy this tool on Vercel · Ship faster with Cursor · Your static site on Cloudflare