JSON Formatter, Validator & Tree Viewer

What this tool does

Paste any block of JSON and this tool beautifies it with proper indentation, validates it against the JSON spec, and shows you exactly where it broke if it doesn't parse. Switch to tree view and you get a collapsible, color-coded outline of the whole structure — handy for digging through a deeply nested API response without losing your place. Everything runs in your browser; nothing you paste is ever uploaded anywhere, which matters if the JSON you're debugging has an API key or customer data in it.

Who it's for

Backend and frontend developers checking an API response, QA engineers comparing payloads, anyone pasting a config file into a bug report and wanting it readable first. It's also just a fast way to answer "is this valid JSON?" when a build is failing on a malformed config.

How to use it

• Paste your JSON into the box, or click Upload .json to load a file from disk.
• Click Beautify to pretty-print it with your chosen indent size, or Minify to strip it down to one line.
• Turn on Sort object keys if you want a deterministic, alphabetized diff-friendly output.
• Switch between the Text and Tree views to read the raw output or explore it as a collapsible outline.
• Use Copy or Download .json to grab the result.

Real-world uses

Formatting a minified API response so you can actually read it. Validating a package.json or config file after a manual edit before it breaks your build. Sorting keys so two JSON files diff cleanly in version control. Exploring a large, deeply nested payload node by node instead of scrolling through one giant line.

Frequently asked questions

Does this JSON validator check against a schema?

No — it validates that your input is syntactically correct JSON (matching braces, quoted keys, valid types), not that it matches a particular schema. For schema validation you'd need a JSON Schema tool, which is a different job.

Why does it say "Unexpected token" when my JSON looks fine?

The most common culprits are a trailing comma after the last item, single quotes instead of double quotes, or an unquoted key — all valid in JavaScript object literals but not in strict JSON. The error message includes the line and column so you can jump straight to it.

Is there a size limit?

There's no hard limit built into the tool, but very large files (tens of megabytes) will be slower to parse and render in tree view since it all happens in your browser's memory.

Can I convert JSON to a table or CSV instead?

Yes — use the site's JSON to HTML Table & CSV Converter for that. This tool is specifically for formatting, validating, and visually exploring JSON as JSON.

Will my data be sent to a server?

No. Parsing, formatting, and the tree view all run locally in JavaScript in your browser tab — nothing is transmitted anywhere.