📋 JSON Formatter

About this JSON Formatter

JSON (JavaScript Object Notation) is the lingua franca of modern web APIs. Every time a browser talks to a server, a mobile app loads a feed, or two services exchange data, JSON is usually the wire format. When you get a response from an API as one giant unformatted line, or you copy a payload out of network dev tools, you either need to pretty-print it (so a human can read it) or minify it (so a machine can transmit it faster). This tool does both.

Everything runs in your browser. Paste the JSON on the left, pick Pretty or Minify, hit Format. Your payload never leaves the tab — we have no server-side JSON endpoint, and there is no upload. That matters because payloads often contain auth tokens, API keys, customer records, or anything else you shouldn’t paste into a random online tool.

Pretty vs Minify

• Pretty — adds indentation and line breaks so you can read nested structures. Standard indent: 2 spaces, matching most team style guides; equivalent to JSON.stringify(obj, null, 2).
• Minify — strips all whitespace, producing the smallest valid representation. Useful before embedding JSON in a URL, a log line, or a query parameter; equivalent to JSON.stringify(obj).

Common errors (and how to fix them)

• “Unexpected token” — usually a missing comma between fields, or a trailing comma after the last item (JSON doesn’t allow trailing commas even though JavaScript does).
• “Unexpected string in JSON” — often a single quote where a double quote belongs. JSON keys and strings must use " double quotes.
• “Unexpected end of JSON input” — you probably copied a truncated payload. Check that the opening { or [ has a matching close.
• Comments — JSON does not support // or /* */ comments. If you have those, you’re looking at JSONC or a config file, not plain JSON.

What about very large files?

This tool works on everything your browser can hold in memory — typically several MB without breaking a sweat on a modern laptop. For multi-hundred-MB JSON dumps, use a streaming command-line tool like jq instead. For sensitive payloads where even browser processing is off-limits, use an offline editor or your own scripts. See our Privacy Policy for how ZakGT treats data you paste into our tools in general.