JSON formatter and validator

How to use it

1. Paste the JSON into the left pane, or drop a .json file on the dropzone.
2. Press Format for indented output, Minify to strip whitespace, Validate to check without reformatting. Ctrl or Cmd with Enter also formats.
3. Set the indent to two spaces, four spaces or a tab, and tick sort keys to make two payloads comparable.
4. If the parse fails, the status line names the line and column and the output pane shows the character in context with the cursor placed on it.

Where the parsing happens

In your tab, by the same JSON engine your browser already uses. No request is made, which matters more than it sounds: a payload from a tracker or a postback usually carries click IDs, payouts and sometimes a token, and pasting that into a server-side formatter hands it to someone else. Here the data never leaves the page, and the tool keeps working with the network off.

The error reporting is the part worth having. Browsers word parse failures differently — Chrome, Firefox and Safari each phrase the same broken comma their own way, and only some of them report a position. The tool normalises the message, derives line and column when the engine omits them, and highlights the offending character in a window of surrounding text, so you fix the payload instead of decoding the error.

Lenient parsing

Strict JSON has no comments and no trailing commas, which is correct and inconvenient: configuration files written by hand are full of both. Tick lenient parse and the tool strips line and block comments and trailing commas outside of strings before parsing, then gives you valid JSON back. A comma inside a string literal is left alone, so a value like "a, b" survives.

What the counters mean

• Result size — bytes of the output, measured after encoding, not characters.
• Keys — object keys across the whole tree, nested ones included.
• Nesting depth — the deepest chain of objects and arrays. Worth a look before you hand the payload to a parser with a depth limit.
• Array items — elements across all arrays in the document.

Minify, and by how much

Minifying drops every optional space and newline. The hint over the output pane shows the saving as a percentage of what you pasted, which is the number to quote when someone asks whether formatting costs anything in transit. On a deeply indented payload the answer is usually between 20 and 40 percent before compression, and close to nothing after gzip.

Questions