JSON Formatter & Validator

How to use the JSON Formatter

1. 1

   Paste your JSON into the left box, or click Load sample to try it with example data.

2. 2

   Choose an indent of 2 spaces, 4 spaces or a tab.

3. 3

   Press Format to beautify, Minify to strip whitespace, Validate to only check syntax, or Sort keys to order every object alphabetically.

4. 4

   If there is a mistake, read the red message: it gives the line, the column and a caret under the problem character.

5. 5

   Copy the result, download it as a .json file, or switch to Tree view to fold and unfold nested objects.

Why API responses arrive as one long line

Servers almost always send JSON minified. Spaces and line breaks mean nothing to a parser, so dropping them saves bandwidth on every request. That is great for the network and terrible for you when you are trying to find one field inside a 40 KB response from a payment gateway or a GST e-invoice API.

Formatting puts each key on its own line and indents nested objects so the structure becomes visible. You can see at a glance that items is an array of three objects, that address sits inside customer, and that a value you expected to be a number is actually a string in quotes.

The tool never changes your data while formatting. It parses the text with the browser's own JSON.parse and writes it back with JSON.stringify, so what you get is the same document with different whitespace.

Common JSON errors and how to fix them

JSON looks like a JavaScript object, but the rules are much stricter. Nearly every error people hit comes from writing JavaScript habits into a JSON file. These are the ones this validator catches most often, with the exact fix.

When the parser stops, the error box shows the line and column and draws a caret under the character where things went wrong. Remember that the real mistake is sometimes just before that spot. A missing comma, for example, is reported at the start of the next key, because that is where the parser realised something was off.

Different browsers word their JSON errors differently, and Safari does not give a position at all. This page runs its own small scanner to find the position and describe the problem in plain words, then also shows the browser's original message underneath for reference.

Format, minify, validate or sort: which button to use

Format is what you want most of the time. Two spaces is the common style in JavaScript projects, four spaces is typical in Python and Java codebases, and a tab lets each person's editor decide the width.

Minify does the opposite and removes every space that is not inside a string. Use it before pasting JSON into an environment variable, a single-line config field or a request body where size matters. The success message tells you how many bytes you saved.

Validate only checks syntax and confirms the document is valid.

Sort keys reorders the keys of every object, at every level, alphabetically. Arrays keep their original order because order in an array carries meaning. Sorting is the trick for comparing two API responses: sort both, then run them through a diff tool and only the real differences show up.

Reading the stats and the tree view

After a successful run you see the output size in bytes, the total number of keys across all levels, the nesting depth and the type of the top-level value. Depth is a quick sanity check. If a simple settings file reports a depth of 12, something is probably wrapped inside itself by mistake.

The tree view is useful for large documents. Nodes open two levels deep by default, and each collapsed node shows how many keys or items it holds, so you can jump straight to the part you care about without scrolling through thousands of lines. Very large arrays show the first 500 entries in the tree; the text output always has everything.

Things a JSON formatter will quietly change

Because the tool parses and re-serialises your data, a few edge cases are worth knowing about before you trust the output for production.

• Duplicate keys: JSON.parse keeps only the last value for a repeated key, so {"a": 1, "a": 2} becomes {"a": 2}. If your output has fewer keys than you expected, look for duplicates.
• Big integers: JavaScript numbers are exact only up to 9007199254740991. A 19-digit order ID or a Twitter-style snowflake ID written as a number will be rounded. Ask the API to send such IDs as strings.
• Number formatting: 1.0 becomes 1 and 1e3 becomes 1000. The value is the same, the text is not.
• Escapes: \u20B9 is written back as the actual ₹ character. It is identical JSON, just more readable.

Files like tsconfig.json or VS Code's settings.json allow comments and trailing commas because they use a relaxed format often called JSONC. Strict JSON parsers reject those, so this validator will flag them. That is correct behaviour, not a bug.

Is it safe to paste production data here?

The formatting, validation and tree view all run in JavaScript inside your browser tab. The JSON you paste is not uploaded, logged or stored, and it is gone when you close or refresh the page. That matters when the payload contains customer phone numbers, PAN details or access tokens.