Validate JSON

$0.003 per call · failed calls are never charged · no account or API key needed

Check whether text is valid JSON. Returns valid true/false, the parsed value's type and size, and for invalid input the error message with line and column. Use before parsing an LLM's or an API's output.

Run it free (25 free calls) Buy credits by card (from $5) Example result (JSON)

Inputs

NameTypeDescription
text (required)stringThe JSON text to check (up to 20,000 characters)

Request

Over HTTP, with a card key from /credits:

curl -H "Authorization: Bearer adt_…" "https://agent-data-tools.revmesh2074.workers.dev/json/validate?text=%7B%22a%22%3A1%7D"

Or one of your 25 free calls, no key:

curl "https://agent-data-tools.revmesh2074.workers.dev/json/validate?text=%7B%22a%22%3A1%7D&trial=1"

Without a key, the same URL answers 402 Payment Required with x402 and MPP terms, so an agent with a wallet pays per call in USDC (Base, Polygon, Arbitrum, Monad, World Chain or Tempo) and retries.

Example result

{
  "valid": true,
  "type": "object",
  "keys": 1
}

From an AI agent (MCP)

Add the MCP server to Claude, Cursor or any MCP client. This tool is json_validate, and the first 25 successful calls are free:

https://agent-data-tools.revmesh2074.workers.dev/mcp

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