How to Format and Validate JSON Online (Step-by-Step Guide)
To format JSON, paste it into the JSON Formatter on pdfseotools.com – it is indented into a readable tree instantly. To check it for errors, use the JSON Validator, which flags problems such as trailing commas or single quotes. Both run in your browser, so your data stays on your device.
Key facts
- Runs in the browser – JSON is not uploaded
- Formatter: readable, indented tree view
- Validator: highlights syntax errors
- Related: JSON Viewer, Editor, Beautifier, JSON to XML
How to format and validate JSON – step by step
✓Step 1: Paste your JSON
🧑💻 Open the JSON Formatter and paste the JSON from an API response, config file or log.
Step 2: Format it
Press the button to turn it into an indented, collapsible view.
Step 3: Validate if it fails
If you see an "invalid JSON" message, paste it into the JSON Validator to find the exact problem.
Step 4: Fix and copy
Correct the error, format again and copy the clean JSON.
The most common JSON errors
| Error | Wrong | Right |
|---|---|---|
| Trailing comma | {"a": 1, "b": 2,} | {"a": 1, "b": 2} |
| Single quotes | {'name': 'Ravi'} | {"name": "Ravi"} |
| Unquoted key | {name: "Ravi"} | {"name": "Ravi"} |
| Comment | {"a": 1 // note} | {"a": 1} |
| Missing bracket | {"list": [1, 2} | {"list": [1, 2]} |
JSON rules in one minute
✓- Data is in key–value pairs: "key": value.
- Keys and text values use double quotes.
- Values can be text, numbers, true, false, null, objects {} or arrays [].
- Items are separated by commas – but not after the last one.
Other JSON tools
- JSON Viewer – explore large JSON as a tree.
- JSON Editor – edit values directly.
- JSON Beautifier – pretty-print in one click.
- JSON to XML and XML to JSON – convert between formats.
Open the JSON Formatter on pdfseotools.com – free, no sign-up and it works on any device.
Domande frequenti
Is my JSON sent to your server?
No. The JSON Formatter and Validator run in your browser, so the data stays on your device.
What is the difference between formatting and validating?
Formatting adds indentation and line breaks so JSON is easy to read. Validating checks that it follows JSON rules and points out errors.
Why does my JSON fail validation?
Common causes: a trailing comma, single quotes instead of double quotes, keys without quotes, comments, or a missing bracket.
Can I minify JSON?
Yes – use the JSON Editor or remove whitespace for compact output. Formatting and minifying do not change the data.
Can JSON contain comments?
Standard JSON does not allow comments. Remove them, or use a format such as JSON5 only where your software supports it.
Can I convert JSON to XML?
Yes. Use JSON to XML, and XML to JSON for the reverse.
Summary
Format to read, validate to fix – and your data never leaves your browser. Start with the JSON Formatter and see all free developer tools.
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