{ }JSON Formatter / Validator
Validate JSON with precise error messages, pretty-print it with any indent, and inspect its top-level type and element counts.
Worked examples
Compact object → pretty
GET /api/v1/dev/json-formatter?json=%7B%22name%22%3A%22Ada%22%2C%22langs%22%3A%5B%22ts%22%2C%22py%22%5D%2C%22active%22%3Atrue%7D&indent=2
Result: { "name": "Ada", "langs": [ "ts", "py" ], "active": true }
Array of numbers
GET /api/v1/dev/json-formatter?json=%5B1%2C2%2C3%5D&indent=2
Result: [ 1, 2, 3 ]
Nested structure
GET /api/v1/dev/json-formatter?json=%7B%22user%22%3A%7B%22id%22%3A7%2C%22tags%22%3A%5B%22a%22%2C%22b%22%5D%7D%7D&indent=4
Result: { "user": { "id": 7, "tags": [ "a", "b" ] } }
Machine API (x402)
$0.001 / callThis tool is also a JSON API for AI agents. Requests without payment receive 402 Payment Required plus instructions; agents pay USDC on Base via the x402 protocol — no accounts, no API keys.
GET /api/v1/dev/json-formatter?json=%7B%22name%22%3A%22Ada%22%2C%22langs%22%3A%5B%22ts%22%2C%22py%22%5D%2C%22active%22%3Atrue%7D&indent=2 HTTP/1.1
Host: agenttools-hub.vercel.app
→ 402 (payment required, instructions in headers)
→ 200 (after X-PAYMENT header; JSON body below)
{
"tool": "dev/json-formatter",
"input": {"json":"{\"name\":\"Ada\",\"langs\":[\"ts\",\"py\"],\"active\":true}","indent":2},
"result": { "value": null, "answer": "{
"name": "Ada",
"langs": [
"ts",
"py"
],
"active": true
}" }
}Agent docs: /llms.txt · OpenAPI spec · integration guide
About this tool
Paste JSON to validate it, pretty-print it with your preferred indent, and see its shape — top-level type, key counts and size before and after formatting. Parse errors are surfaced with their position so you can fix them fast.
JSON.parse(text) → value · JSON.stringify(value, null, indent) → formatted text
Frequently asked questions
What are the most common JSON errors?
Trailing commas, single quotes instead of double quotes, unquoted keys, and comments (JSON has none). The error message pinpoints the position.
Is my data stored anywhere?
No. Formatting is a pure function executed in the request; nothing is logged or persisted.