Format and check JSON in your browser
Paste JSON or drop a file. The tool formats it and shows the exact line of any mistake. Fix the usual mistakes in one click, and explore the data as a tree. It all happens in your browser, even for files of 50 MB and more.
- Free, no sign-up
- Runs in your browser. Your files never leave your device.
- Updated
Input
Paste JSON, drop a file, or try a sample
It’s checked as you type, with the exact line and column of any mistake. Files up to 1 GB open here, in your browser.
is loaded.
Its text stays out of the editor so the page stays quick. Use the layout, sort, tree and path filter on the right, then copy or download the result.
The result shows here
Formatted, as a tree you can fold, as YAML or as CSV. Copy it or download the file.
Your JSON stays in this browser tab. Nothing is uploaded, and there is no account, ad or size limit.
To format JSON, paste it into the input. The formatter checks it as you type and shows it indented by 2 spaces, 4 spaces or a tab (or minified). It points to the exact line and column of any mistake. It runs entirely in your browser, keeps your numbers exactly as typed, and handles files of 50 MB and more.
How do I format and validate JSON?
- Paste your JSON, drop a file anywhere on the tool, or click Open a file. No JSON handy? Try a sample loads one.
- If it is valid, the status line says so and the right side shows it formatted. Pick 2 spaces, 4 spaces, Tab or Minified under Layout, and tick Sort keys to put every object’s keys in order.
- If it is not valid, you get the line, the column, a plain-English reason and a marker in the editor’s gutter. Click Fix it for me for the common mistakes, or Show the spot to jump there.
- Copy the result, Download it as a file, or use Replace input with the result in the More menu to tidy the input in place.
What mistakes make JSON invalid?
| You wrote | JSON needs |
|---|---|
{"a": 1,} (trailing comma) | No comma after the last item |
{'a': 'b'} | Double quotes around keys and strings |
{a: 1} | Keys in double quotes: "a" |
// note or /* note */ | No comments at all |
undefined, NaN, None | null, true or false |
| A raw line break inside a string | \n written as an escape |
[1 2] | A comma between items |
How do I explore a large JSON file?
Switch to the Tree tab to open and fold levels, or search keys and values (Enter steps through matches). Select any row and press P to copy its path, such as $.orders[0].customer.name. Press V to copy its value.
To pull out only what you need, type a path in the filter box. The JSON, tree, YAML and CSV views then show just that. Lists of a million items open at once, because the tool draws only the rows on screen.
Does it change my numbers or key order?
Numbers stay exactly as you typed them. That includes long IDs such as 12345678901234567890 and values such as 1.50 or 1E5, which most formatters quietly round or rewrite. Keys keep their order unless you tick Sort keys. Unicode, emoji and right-to-left text pass through unchanged.
How is this different from other free JSON tools?
Checked on 4 November 2026: jsonformatter.org says anything you save without logging in is public and expires within a day, and keeps longer saves for logged-in users (jsonformatter.org); JSON Crack’s editor shows an “Upgrade to Pro Editor” link (jsoncrack.com/editor). Here nothing is saved on a server, there is no tier, and the 50 MB limit most tools hit does not apply. Parsing runs in a background thread with progress.
Keyboard shortcuts
| Open a file | Ctrl/⌘ + O |
| Copy the result, download it | Ctrl/⌘ + Enter, Ctrl/⌘ + S |
| Replace the input with the result | Ctrl/⌘ + Shift + F |
| Fix common mistakes | Alt + F |
| Filter with a path | / |
| Tree: move, open, close | ↑ ↓ → ← |
| All shortcuts | ? |
Questions
Is my JSON uploaded anywhere?
No. Code in your browser tab reads and formats your JSON, and your device opens the files. The page sends no copy of your data anywhere. You can check this in your browser’s network panel. That makes it fine for API responses, config files and exports with private fields in them.
How big a file can it open?
Files up to 1 GB are accepted. A background thread reads and parses the file, with a progress bar, so the page keeps responding. A 50 MB file usually opens in a few seconds on a laptop. Very large files keep their text out of the editor. You explore them with the tree, the path filter, and the copy and download buttons.
How does it find the error in my JSON?
It checks the text as you type. It names the first mistake with its exact line and column and marks the spot in the editor’s gutter. It says in plain words what to change: a trailing comma, single quotes, a missing comma, an unquoted key, a comment, and so on. “Fix issues” repairs the common ones for you.
What does “Fix issues” change?
It removes comments and trailing or doubled commas. It adds missing commas. It changes single and curly quotes to double quotes and puts quotes around bare keys. It replaces undefined, NaN and Python’s None, True and False with valid JSON values. It closes unclosed brackets and wraps JSON Lines into one list. It tells you exactly what it changed, and Undo restores your original.
Does formatting change my numbers?
No. Numbers keep the digits you typed. 12345678901234567890 stays whole instead of being rounded, and 1.50 stays 1.50. Many formatters pass numbers through JavaScript’s parser, which silently rounds integers above 9,007,199,254,740,991. The status line tells you when the tool kept numbers exactly.
What can I convert JSON to?
Use the tabs above the result: formatted JSON (2 spaces, 4 spaces, a tab or minified), a collapsible tree, YAML, or CSV. CSV works on a list of objects and flattens nested objects into columns such as address.city. “Read the input as YAML” in the More menu converts YAML to JSON, the other way.
How do I pull one value out of a big document?
Type a path in the filter box. Use $.orders[*].customer.name for every customer name, $..sku for every sku at any depth, or $.orders[?(@.total > 100)] for orders over 100. The JSON, tree, YAML and CSV views then show only the result. Click the info icon for examples.
Is there a limit, a sign-up or a paid tier?
No. There is no account, no daily limit, no file-size paywall and no ads. Sorting, the tree, paths, YAML, CSV and very large files are all free. The tool saves nothing you type unless you tick “Keep my last input on this device”. Unticking it deletes what was kept.
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