JSON Formatter Online
Beautify, validate, sort, and minify JSON — privately, in your browser. Live errors point to the line.
How to format JSON online
Paste your JSON into the Input box on the left. The right side updates instantly with a beautified version. Switch to Minify to strip whitespace, or toggle Sort keys A→Z to get canonical, diff-friendly output. Errors are caught immediately — you get the exact engine message and a line/column pointer so you can fix typos in seconds.
Why a local JSON formatter matters
Most JSON you paste into a formatter contains something sensitive — production API responses, user PII, JWTs, internal IDs. Online formatters that POST your data to a server log everything they receive. ToolChop runs the entire format pipeline in your browser using the built-in JSON.parse and JSON.stringify. Nothing is uploaded, ever. We could not see your JSON if we wanted to.
What you can do
- Beautify with 2-space, 4-space, or tab indent
- Minify to a single dense line
- Validate with a line and column pointer on errors
- Sort object keys alphabetically for canonical output
- See stats — keys, arrays, max depth, bytes
- Copy to clipboard or download as
.json
Frequently asked questions
How do I format JSON online for free?
Paste your JSON into the Input box. The Output box on the right updates instantly with formatted JSON. Pick 2 spaces, 4 spaces, or tab indent. Click Copy or Download. No account, no upload, no daily limit.
Does ToolChop upload my JSON?
No. The entire format, validate, sort, and minify pipeline runs in your browser. Your JSON never leaves your device — there is no upload, no temporary storage, and no copy on our servers. That is the main reason to use ToolChop for JSON containing API responses, secrets, or PII.
What is the difference between format and minify?
Format (beautify, pretty-print) adds indentation and line breaks so the structure is readable by humans. Minify strips every byte of whitespace so the JSON is a single dense line — ideal for HTTP payloads or string literals. Both produce semantically identical JSON.
How does the validator work?
The tool parses your input with the browser's built-in JSON.parse. If it fails, we surface the exact engine error message and try to point at the line and column number. Common causes: trailing commas, unquoted keys, single quotes instead of double, and unescaped backslashes.
What does Sort keys A→Z do?
It recursively sorts every object's keys alphabetically before output. This produces canonical JSON — two semantically equal documents become byte-identical, which is great for diffing API snapshots, building reproducible build outputs, or detecting drift in config files.
Why is my JSON invalid even though it looks fine?
Three usual suspects. (1) Trailing commas: JSON does not allow them; JavaScript does. (2) Single quotes: JSON only accepts double quotes around strings and keys. (3) Comments: JSON has no comment syntax — // or /* */ will fail. JSON5 and JSONC both fix these, but standard JSON does not.
Can I format JSON with comments (JSONC)?
Not yet. JSON.parse rejects comments. As a workaround, strip the // single-line and /* */ block comments first — but be careful, they may appear inside strings. A future ToolChop release may add a JSONC mode; let us know if you need it.
Does the tool handle huge JSON files?
Yes — the limiting factor is your browser. We have formatted 50 MB JSON files in modern Chrome without issue. Above that, the browser may stutter while pretty-printing because JSON.stringify is synchronous. For multi-GB JSON, use a streaming CLI tool like jq.
Is the JSON formatted in-place or as a copy?
As a copy. Your original input stays untouched in the Input box; the formatted result appears in the Output box on the right. This lets you compare them side by side and edit the input incrementally.
Will the formatter change my numbers or booleans?
No. The values are parsed, then re-serialized identically. The only intentional difference is whitespace. Note that JSON specifies numbers as 64-bit floats — extremely large integers (above 2⁵³) can lose precision in any JSON parser, including this one. For big integers, send them as strings.
Can I format an array, a number, or a string by itself?
Yes. JSON allows any value at the top level — array, object, string, number, boolean, or null. Paste in `[1, 2, 3]` or `"hello"` and the tool will accept it.
What is canonical JSON and why does it matter?
Canonical JSON is a deterministic byte-level representation — same input, always same output. Achieved by sorting object keys and using a fixed escape strategy. It matters for signing JSON (any non-canonical reordering would invalidate signatures), building reproducible artifacts, and writing diff-friendly fixtures.
Why use ToolChop instead of an online formatter that uploads my data?
Privacy. Online JSON formatters that POST your payload to a server log everything they receive — including production API responses, JWTs, customer PII, and secrets. ToolChop runs entirely in your browser so the JSON never leaves your machine. We could not see it if we wanted to.