About the JSON Validator
When a config file or API payload refuses to parse, the browser's error message is rarely enough. This validator reports the failing line and column, counts the document's structure, and confirms whether the JSON is valid.
How to use it
- 1Paste the JSONInclude the whole document — the validator checks the complete structure.
- 2Run validationValid documents are summarised by type, key count and nesting depth; invalid ones report the failing position.
- 3Fix and re-checkEdit the input and validate again until the document parses cleanly.
Why use this json validator?
- Nothing leaves your device. The work happens in your browser tab. There is no upload endpoint in this app, so your files and text cannot be stored, logged or seen by us.
- No upload wait. You skip the round trip to a server entirely. Results are limited by your own CPU, not by network speed or queue size.
- Free, no account, no quotas. No sign-up wall, no watermark, no daily limit. Optional accounts only exist to save favourites and presets across devices.
Frequently asked questions
Is my JSON safe to use here?
Yes. This tool runs entirely in your browser using JavaScript. Nothing you paste or open is sent to a server, and the page keeps no copy after you close it.
Do I need to create an account?
No. Every tool is fully usable without signing in. An account only adds saved favourites and reusable presets.
Does it work on a phone?
Yes. The interface is mobile-first with large touch targets and a stacked layout, so it works on phones and tablets as well as desktops.
What is the most common JSON syntax error?
A trailing comma before a closing brace or bracket. JavaScript allows it, JSON does not. The second most common is an unquoted object key.
Can it validate JSON Lines or NDJSON?
Not directly, because each line is a separate document. Validate one line at a time, or convert the file to a JSON array first.