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JSON Formatter

By James Nicolaus ·

JSON Formatter in dark mode showing a pasted API response on the left and a syntax-highlighted formatted output on the right with collapsible tree-view nodes and stats showing key, array, and depth counts
JSON Formatter — syntax-highlighted output with tree view and depth stats.

How to Use

  1. Paste or type your JSON into the text area. The tool automatically formats when you paste.
  2. Click Format (or press Ctrl+Enter) to beautify the JSON with syntax highlighting.
  3. Click Minify to compress the JSON into a single line with no whitespace.
  4. Click Validate to check if the JSON is valid without reformatting.
  5. Switch between Formatted and Tree View to explore the data structure visually.
  6. Click Copy to copy the formatted output to your clipboard.

Features

  • Syntax highlighting — keys, strings, numbers, booleans, and null values are color-coded for easy reading.
  • Error location — when JSON is invalid, the tool shows the exact line and column where the error occurs.
  • Tree view — collapse and expand objects and arrays to explore deeply nested structures.
  • Stats — see key counts, object/array counts, and nesting depth at a glance.
  • Indentation options — choose between 2 spaces, 4 spaces, or tabs.
  • Auto-format on paste — just paste and the JSON is formatted instantly.

Tips

  • Press Tab in the editor to insert indentation instead of moving focus.
  • Use Ctrl+Enter (Cmd+Enter on Mac) as a quick shortcut to format.
  • The tree view is great for exploring large API responses — click the arrows to collapse sections you don't need.
  • Minify is useful for reducing payload size before sending JSON in API requests.

Frequently Asked Questions

What does JSON formatting do?

Formatting (also called beautifying or pretty-printing) adds indentation and line breaks to make JSON human-readable. It applies syntax highlighting to distinguish keys, strings, numbers, booleans, and null values.

How does the validator pinpoint errors?

When your JSON is invalid, the tool uses the browser's JSON parser to catch the error and displays the exact line number and column position where the problem occurs.

What indentation options are available?

You can choose between 2 spaces, 4 spaces, or tabs for indentation when formatting your JSON.

Is my JSON data sent to a server?

No. All formatting, validation, and minification runs entirely in your browser. Your JSON data never leaves your device.

What is the keyboard shortcut for formatting?

Press Ctrl+Enter on Windows/Linux or Cmd+Enter on Mac to format your JSON instantly without clicking the Format button.

About

JSON Formatter & Validator helps developers quickly format, validate, and explore JSON data. It catches syntax errors and pinpoints their location, making it easy to debug malformed JSON from APIs, config files, or logs.

Everything runs in your browser — your data is never sent to a server. No accounts, no installs, works on any modern browser.

From the build: the line-and-column error reporting was harder than the formatting itself. `JSON.parse` throws a single message like "Unexpected token } in JSON at position 247", and "position 247" is useless when you're staring at 800 lines of pasted config. We catch the error, walk the input string up to that byte offset, count newlines and column offset, and surface "line 12, column 4". Pretty-printing is just `JSON.stringify(parsed, null, indent)` — the browser does the heavy lifting — and the syntax highlighter is a single regex pass over the stringified output, not a tokenizer.