Format JSON and Validate It: Indents, Sorting, Tree View

How to format JSON and check it in one pass

Paste text into the input box, drop a .json or .txt file on it, or click Open file for anything up to 50 MB. Checking starts as you type, so you know whether the input is sound before you press a single button.

• A green Valid JSON status reports the number of top-level items, the total keys, the nesting depth and the size in bytes. An export that should hold 1,200 orders but reports 1,199 items deserves a second look.
• If the check fails, the status line names the line and column and puts a caret under the character where parsing stopped; the real culprit is usually one token to the left.
• Beautify re-indents everything with 2 spaces, 4 spaces or a tab. Nothing about the data changes, only line breaks and indentation.
• Copy the result or save it with the .json download button when you are done.

New to the notation? There are only six kinds of value. Curly braces hold an object of named fields, square brackets hold a list called an array, text sits in double quotes, numbers such as 19.99 are bare, true and false are lowercase switches, and null means empty or unknown, which is not the same as zero. Each step of indentation means you are inside the object or list above, so a price indented three levels deep belongs to one line item, not the whole order.

Choose an indent style, then sort keys for clean diffs

No indent is correct in the abstract; a consistent one is. Two spaces is the default in npm's package.json, Prettier and most JavaScript projects. Four spaces is familiar from Python, where json.dumps(data, indent=4) is a common idiom. Tabs let each reader pick their own width.

• The indent menu beside Beautify switches between the three styles and reformats instantly when the input is already valid.
• Indentation adds bytes: a deeply nested response can grow by a third or more, so keep the compact version for production traffic.
• Tick Sort keys before Beautify and every object is ordered alphabetically at every level, not only the top one. Array order is preserved because in arrays position carries meaning.
• Beautify both versions of a payload with identical settings, then paste them into a text diff tool; only the real changes remain.
• Do not commit sorted output over a file whose key order is deliberate, such as a manifest where scripts are grouped by hand, or with an indent your repository does not use, or every line will show as changed.

Find one value in a big file with the tree and JSONPath

Scrolling 20,000 lines is slow and error-prone. The Tree tab shows the same data as collapsible nodes that render their children only when opened, so multi-megabyte exports stay responsive, and each collapsed node shows how many keys or items it holds.

• Click any key and its path, for example $.line_items[0].price, is copied and placed in the query box. Sending that path to a developer is far clearer than a screenshot.
• The JSONPath tab searches the whole document: $..email lists every email field at any depth, and $..book[?(@.price < 10)].title returns titles under ten dollars.
• $..* flattens everything into a single list, handy when you know the value you are hunting for but not its field name.
• Starter buttons under the query box insert ready-made expressions you can edit to learn the syntax.

For a list of flat records you want in a spreadsheet, GrabCast's CSV to JSON converter also works in reverse and produces rows Excel or Google Sheets can open.

What formatting can change, and what validation cannot see

Beautifying means parsing and writing the data back out, and a JavaScript parser has limits you should know before pasting formatted output into a live system.

• Integers above 9,007,199,254,740,991 lose precision: 9007199254740993 comes back as 9007199254740992. This is why many APIs send large IDs as strings.
• Duplicate keys are accepted but only the last one survives, so a repeated field silently disappears from the output.
• The Repair button fixes comments, single quotes and trailing commas, but it also turns NaN or Infinity into null, which changes the data; read its list of fixes before trusting the result.
• Curly quotes from Word, Google Docs or Slack break every string they touch; edit by hand only in a plain text editor.
• A green status proves the syntax is well formed, not that the content is right. A payload can pass and still miss a required field or violate your schema.

Everything above runs inside your browser tab. Customer emails, addresses and tokens in a webhook are not uploaded, though your company's data policy still decides where such records may be opened.

If your config is in YAML rather than JSON, convert it first with the YAML to JSON converter and then format it as above.

Step-by-step

Common mistakes to avoid

Pro tips

Frequently asked questions