Free JSON Formatter
Paste messy JSON to get it cleanly indented and validated, with the exact position of any syntax error. Minify it again when you need the smallest possible payload.
What is the JSON formatter?
A JSON formatter takes JSON that arrived as one unreadable line and lays it out with proper indentation so a human can follow the structure. It also validates as it goes: if there's a stray comma, a missing bracket or a single quote where a double quote belongs, it reports the problem and where it occurred rather than silently failing. JSON is the format APIs, configuration files and log exports use everywhere, so reading and checking it is a daily task for developers and increasingly for marketers and analysts working with exports. This formatter runs entirely in your browser, which matters because API responses routinely contain keys, tokens and customer data that shouldn't be pasted into a stranger's server.
How our free JSON formatter works
Paste your JSON
Drop in a raw API response, config file or export — however messy.
Pick the indentation
Two or four spaces for readability, or Minify to strip whitespace entirely.
Read the result
Valid JSON is formatted with a node count; invalid JSON shows the error and its position.
Who uses our free JSON formatter?
Developers
Inspect API responses and debug configuration files quickly.
QA and support engineers
Read log payloads attached to a bug report.
Analysts and marketers
Make sense of JSON exports from analytics and marketing platforms.
Anyone editing a config file
Validate JSON before deploying it and breaking something.
Why use the JSON formatter?
Pinpoints syntax errors
Reports what's wrong and where, instead of just refusing to parse.
Format or minify
Readable indentation while you work, minified when you need the smallest payload.
Safe for real data
Nothing is uploaded, so API responses containing tokens or customer data stay local.
Tips for getting the best results
Trailing commas are the usual culprit
JSON, unlike JavaScript, forbids a comma after the last item in an object or array. It's the single most common error.
Strings need double quotes
Single quotes are valid JavaScript but invalid JSON. Keys must be double-quoted too.
Minify for production, format for reading
Minified JSON transfers faster; indented JSON is for humans. Keep both uses separate.
Strip secrets before sharing
Even though this tool is local, remove API keys and tokens before pasting a payload into a ticket or chat.
Common problems and how to fix them
“Unexpected token” — what does that mean?
There's a character where JSON didn't expect one. The position in the message points at it — most often a trailing comma, a single quote, or an unquoted key.
“Unexpected end of JSON input”
A bracket or brace was never closed, usually because the text was truncated when it was copied. Re-copy the full payload.
My JSON is valid elsewhere but fails here
Some tools accept JavaScript object notation rather than strict JSON. Comments, single quotes and trailing commas are all invalid in real JSON.
Frequently asked questions
What does a JSON formatter do?
It re-indents JSON so the structure is readable, and validates it at the same time — reporting any syntax error and where it occurred.
Is my JSON data uploaded?
No. Formatting and validation happen in your browser, which is why it's safe to paste API responses containing real data.
What's the difference between formatting and minifying?
Formatting adds indentation and line breaks for readability. Minifying strips all unnecessary whitespace to make the file as small as possible for transmission.
Why is my JSON invalid?
The most common causes are a trailing comma after the last item, single quotes instead of double, unquoted keys, or comments — none of which strict JSON allows.
Is there a size limit?
No fixed limit, though very large payloads take longer since the parsing happens on your device.
