JSON Validator

Validate JSON strings and get pretty-printed or minified output.

POST 1 credit /v1/json-validate

curl -X POST "https://devtools.toolkitapi.io/v1/json-validate" \
  -H "Content-Type: application/json" \
  -d '{"data": "{\"name\": \"Alice\", \"age\": 30}"}'

import httpx

resp = httpx.post(
    "https://devtools.toolkitapi.io/v1/json-validate",
    json={"data": "{\"name\": \"Alice\", \"age\": 30}"},
)
print(resp.json())

const resp = await fetch("https://devtools.toolkitapi.io/v1/json-validate", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
  },
  body: JSON.stringify({"data": "{\"name\": \"Alice\", \"age\": 30}"}),
});
const data = await resp.json();
console.log(data);

# See curl example

Response 200 OK

{
  "valid": true,
  "pretty": "{\n  \"name\": \"Alice\",\n  \"age\": 30\n}",
  "minified": "{\"name\":\"Alice\",\"age\":30}"
}

Try It Live

Description

Validate JSON strings and get pretty-printed or minified output.

How to Use

1

1. Send a POST request with a `data` field containing the raw JSON string you want to validate.

2

2. Inspect the `valid` field in the response. If `true`, the `pretty` and `minified` fields contain the formatted output.

3

3. If `valid` is `false`, use the `error`, `line`, and `column` fields to locate the syntax problem.

About This Tool

JSON Validator checks whether a given string is valid JSON. When the input is valid it returns both a pretty-printed and a minified version. When the input is malformed it returns the exact error location (line and column) so you can fix the problem quickly.

Use it to sanity-check API payloads, config files, or any JSON blob before processing it downstream.

Why Use This Tool

API debugging — Quickly verify that request/response payloads are well-formed
Config validation — Check JSON configuration files before deployment
Pretty-printing — Convert compact JSON into readable indented output
Minification — Shrink JSON payloads for storage or transmission

Frequently Asked Questions

What is the maximum input size?

The validator accepts JSON strings up to 1 MB (1,048,576 characters).

Does it support JSON with comments?

No. The validator uses strict JSON parsing per RFC 8259. Comments, trailing commas, and other non-standard extensions will be flagged as invalid.

Can I use this to format JSON?

Yes — when the input is valid, the `pretty` field returns indented JSON and `minified` returns the most compact representation.

Start using JSON Validator now

Get your free API key and make your first request in under a minute.

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