JSON validate & format

Validate, pretty-print, or minify JSON. Returns parse errors with position when invalid.

Input

Field	Type	Description
json *	string	JSON text to validate/format (max 100KB)
indent	number	Spaces of indentation; 0 = minify (default 2)

Example output

{
  "valid": true,
  "formatted": "{\n  \"a\": 1\n}"
}

Try it — see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/json-format \
  -H "Content-Type: application/json" \
  -d '{"json":"{\"a\":1}","indent":2}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/json-format", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "json": "{\"a\":1}",
    "indent": 2
  }),
});

Related tools