Code & Data
Check JSON and find out exactly what is wrong
Paste JSON to find out whether it parses. When it does not, you get the line and column, the line itself with a caret under the problem, and a sentence explaining what usually causes it.
- Runs in your browser
- No account required
- Free to use
How it works
Validated by the same parser that will reject it later
This uses the browser’s own JSON parser rather than a reimplementation, so “valid here” means valid everywhere — there is no risk of a hand-written validator being more lenient than the thing that eventually has to read the file.
The location is the useful half
A validator that says “invalid” has told you what you already knew. The character offset the engine reports is converted to a line and column and shown against the line itself, so you can see the problem rather than hunt for it.
The cause, in plain English
Each engine message is mapped to what it usually means for your document. A missing colon, an unquoted key, a trailing comma and an unterminated file all produce distinct messages, because they need distinct fixes.
What it does
Line, column and context
The offending line is printed with a caret under the exact character, which is the fastest way to see a missing quote.
Structure when it is valid
Keys, objects, arrays and nesting depth — a quick sanity check that the document is the shape you expected as well as being parseable.
Instant, as you type
No button. Paste and the answer is there, which makes fixing an error and confirming the fix a single motion.
Your data never leaves the page
API responses, config files and exports are exactly the sort of thing that should not be pasted into someone else’s server. Parsing happens in your browser and what you paste is never transmitted — there is no code here that could send it anywhere, even by accident.
Practical advice
Getting a better result
- If the error is on the last line, the cause is usually much earlier — an unclosed bracket is only detected when the file runs out.
- “Unexpected end of JSON input” always means something was never closed. Count your brackets from the top.
- Validating does not mean the data is correct, only that it is well-formed JSON. Checking it against a schema is a different job.
- If you need to see the shape rather than check the syntax, the JSON viewer shows it as a collapsible tree.
Questions
Things people ask
What makes JSON invalid?
Most often: a trailing comma after the last item, keys not in double quotes, single quotes instead of double, a missing comma between values, or a bracket that was never closed. Comments make it invalid too — JSON has none.
Does valid JSON mean my data is right?
No. It means the syntax is correct and any parser will read it. Whether the fields are the ones your application expects is a separate question, answered by validating against a schema rather than by parsing.
Why does the error point at the end of my file?
Because an unclosed bracket or brace is only discovered when the parser runs out of document. The reported position is where it gave up, not where the mistake is — start from the top and check that every opening bracket has a partner.
Related tools
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Open toolJSON to YAML
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Open toolWho builds these
Free tools by day. Websites that earn their keep by trade.
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This tool runs entirely in your browser. Your files are never uploaded.