Swrice Tools JSON Validator
Paste your JSON below, or upload a .json file, to instantly check whether it's valid. Everything happens locally in your browser — nothing is sent to a server. If it's invalid, you'll get the exact line and column of the problem instead of a generic error.
How to use the JSON Validator
- Paste or type your JSON into the box above, or click Upload file to load a .json file directly.
- It validates automatically as you type or upload, or click Validate.
- A "Valid JSON" result also shows the parsed structure formatted for a quick read — use Copy to grab it.
- An invalid result tells you exactly which line and column to check — including duplicate keys, which are legal JSON but usually a mistake.
Frequently asked questions
Is this JSON Validator free to use?
Yes, it is completely free with no sign-up or usage limits.
Is my data uploaded anywhere?
No. Validation happens locally in your browser using JavaScript — your JSON is never sent to a server.
What counts as valid JSON?
Valid JSON needs double-quoted keys and strings, no trailing commas, and only objects, arrays, strings, numbers, booleans or null as values. This tool uses the same parser built into your browser, so a "Valid" result means it will parse correctly anywhere JSON.parse is used.
Does it catch duplicate keys?
Yes. A repeated key in the same object is technically legal JSON — most parsers just silently keep the last value — but it almost always signals a mistake, so this tool flags it as invalid and points to its exact location instead of hiding it.
Can I upload a file to validate?
Yes, click "Upload file" and choose a .json or .txt file. It is read directly in your browser — the file itself is never sent anywhere.
How is this different from the JSON Formatter?
This tool focuses on a clear valid/invalid result with the exact error location. The JSON Formatter also beautifies, minifies, sorts keys and lets you download the result — use it once you know your JSON is valid and want to work with it further.