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JSON Validator

Validate, format, and minify JSON — or explore it in an interactive tree viewer with search, expand/collapse, and a detail panel for any selected node. Load JSON straight from an API by pasting a URL or a full curl command, convert Python dict/list literals (single quotes, True/False/None, tuples, trailing commas) to JSON, and see syntax errors with the exact line and column.

How to use JSON Validator

  1. Paste your JSON — or a Python dict/list — into the input box, or load it from an API by entering a URL or curl command and clicking Fetch.
  2. Use Prettify or Minify, or switch the view to Tree to browse the structure.
  3. In Tree view, search keys and values, expand nodes, and click any node to see its path and full value.

Frequently asked questions

Can I load JSON from a URL or a curl command?
Yes. Paste an API URL or a full curl command into the "Load from URL or curl" box and click Fetch — the request runs from your browser and the response is loaded into the input. curl flags like -X, -H, -d, and -u (basic auth) are parsed, and the result is then formatted and validated like any pasted JSON.
Why does fetching from a URL sometimes fail?
The request is made from your browser, so the target server must allow cross-origin requests (CORS). If it does not, the fetch is blocked by the browser — that is a server-side policy, not a limit of this tool. A wrong URL or being offline will also fail.
How does the JSON tree viewer work?
Switch the view to Tree to see your JSON as a collapsible structure. Search filters and highlights matching keys and values and auto-expands to them, and clicking any node shows its JSONPath and full value in the detail panel — with copy buttons for both.
Can it convert a Python dict to JSON?
Yes. Paste a Python dict or list literal — single quotes, True/False/None, tuples, and trailing commas are all understood — and the formatter outputs valid JSON with proper double quotes and lowercase true/false/null.
Why is my JSON invalid?
Common causes are trailing commas, single quotes instead of double quotes, or unquoted keys. Pure JSON is strict about these, though this tool will also accept Python-style dicts. The validator points to the exact line and column.
Is there a size limit?
No hard limit — it is bounded only by your browser, since parsing happens locally.

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