Stays in your browser
JSON Formatter — Beautify & Validate Online
Free JSON formatter and validator. Paste JSON to beautify, minify, or check for syntax errors. Everything runs locally in your browser.
Working with JSON in practice
JSON is strict on purpose, and that strictness is where most bugs start. A trailing comma, a single-quoted key, or an unescaped newline inside a string makes an entire payload unparseable, and most editors only tell you that something is wrong. Paste the response here and the parser points at the exact line, so you can find the stray character before it reaches your code.
Pretty-printing pays off most when you compare two payloads. Indented JSON diffs cleanly in Git and in code review, so a field that changed shape is visible instead of hidden inside one very long line. When you need to compare a staging response with a production one, pretty-print both and the difference usually shows up in seconds.
Use Minify for the opposite case. Whitespace is pure overhead when a payload is sent over the network or stored in a cache, so stripping it before you embed JSON in a config, a fixture, or a log line keeps those files readable without wasting bytes.
FAQ
- What is a JSON formatter?
- A JSON formatter indents and organizes JSON so API responses and configs are easy to read and debug.
- Is my data uploaded?
- No. Formatting and validation run entirely in your browser.
- Can I minify JSON?
- Yes. Use Minify to strip whitespace for transport or storage.
- Why does my JSON fail to parse?
- Almost always because the file is JavaScript, not JSON. Trailing commas, single quotes, unquoted keys, // comments, NaN and Infinity are all legal in JavaScript object literals and all illegal in JSON. The error position this tool reports is where the parser gave up, so look just before it.
- What is the difference between JSON and a JavaScript object?
- JSON is a text format with a fixed grammar: double-quoted keys, no trailing commas, no comments, and only a few value types. A JavaScript object is a runtime value that happens to look similar. Fixing a failing payload usually means quoting a key or removing a comment, after which the parser is happy and the object still works.
- Is there a size limit for the JSON I paste?
- There is no server limit, because nothing is uploaded. The practical ceiling is your browser's memory, so files of tens of megabytes are fine on a desktop and slower on a phone. If a payload is large enough to freeze the tab, splitting it or filtering it on the server first is usually faster than formatting it here.