JSON Formatter & Validator

What this JSON formatter does

Paste raw, minified, or messy JSON into the box on the left and this tool instantly formats it into clean, readable, indented JSON on the right — while validating it at the same time. If your JSON is broken, it tells you exactly where the error is so you can fix it. Everything runs locally in your browser, so your data is never uploaded to a server or stored anywhere.

Use the Format button (or just type) to beautify JSON with your chosen indentation. Use Minify to strip all whitespace and produce the smallest valid output for production payloads. The Copy button grabs the result to your clipboard in one click.

What is JSON?

JSON (JavaScript Object Notation) is a lightweight, text-based format for storing and exchanging data. It has become the default language of APIs, configuration files, and data interchange across virtually every programming language. A JSON document is built from two structures: objects (unordered key/value pairs wrapped in { }) and arrays (ordered lists wrapped in [ ]). Values can be strings, numbers, booleans, null, objects, or arrays.

Here is a small valid JSON object:

{
  "site": "CodeZips",
  "launched": 2019,
  "open_source": true,
  "topics": ["AI", "programming", "tools"],
  "author": { "name": "CodeZips", "verified": true }
}

Why JSON needs formatting

JSON is often transmitted in minified form — all on one line with no spaces — because that is the most efficient way to send it over a network. That is great for machines but unreadable for humans. When you are debugging an API response, inspecting a config file, or trying to understand a webhook payload, formatted JSON with proper indentation makes the structure obvious at a glance. A good formatter also doubles as a validator: if the JSON won’t format, it isn’t valid, and you’ve found a bug.

Common JSON errors and how to fix them

Trailing commas

Unlike JavaScript objects, JSON does not allow a comma after the last item in an object or array. {"a":1,} is invalid; remove the trailing comma to fix it.

Single quotes instead of double quotes

JSON strings and keys must use double quotes. {'name':'CodeZips'} is invalid JSON — it must be {"name":"CodeZips"}. This is one of the most common mistakes when copying from JavaScript or Python.

Unquoted keys

Every key must be a quoted string. {name:"CodeZips"} fails because name is not quoted.

Missing or mismatched brackets

Every { needs a matching } and every [ needs a matching ]. The validator below points to the position where parsing failed, which usually sits right after the unclosed structure.

Comments

Standard JSON does not support comments (// or /* */). If your file has them, it is technically JSONC or a config format, not strict JSON, and will fail validation.

JSON vs JavaScript objects

They look similar but are not the same. JSON is a data format and a strict subset of JavaScript object literal syntax. JavaScript objects allow unquoted keys, single quotes, trailing commas, comments, functions, and undefined — none of which are valid JSON. When you copy an object out of your code and it won’t validate here, one of those differences is usually the reason.

Is it safe to paste sensitive JSON here?

This tool processes everything entirely in your browser using the built-in JSON.parse and JSON.stringify functions. No JSON is sent to any server, logged, or saved. That said, for tokens or credentials, the safest habit is always to use tools that run locally — which this one does.

Frequently asked questions