JSON formatter
Pretty-print or minify JSON, with error checking.
JSON formatter pretty-prints JSON into a readable, indented format, or minifies it down to a single compact line — with clear error messages if the input isn't valid JSON, so you can spot and fix syntax problems.
How to use
- Paste your JSON.
- Click "Format" to pretty-print it, or "Minify" to compress it onto one line.
Common use scenarios
- Formatting a compressed API response into a readable structure for debugging.
- Minifying JSON config data before pasting it into a field that only accepts single-line content.
- Validating that a hand-written or generated JSON snippet is syntactically correct.
- Cleaning up JSON copied from documentation or a chat before using it in code.
✓Content & verification reviewed: 2026-08-25
How we verify JSON formatter
How to confirm the formatted or minified output is exactly equivalent to your input.
Valid JSON round-trips exactly
Paste valid JSON, click Format, then click Minify: the output should collapse back to a single-line, whitespace-free version of the same data — both outputs represent identical data, just with different formatting.
Invalid input shows an error, not a guess
If your input has a syntax problem — a missing comma, an unquoted key, a trailing comma — the tool reports an error rather than attempting to fix or guess at the intended structure, so the original input is preserved unless you edit it yourself.
Indent size controls formatted spacing
The indent size setting controls how many spaces are used per nesting level when pretty-printing — it has no effect on minified output, which always uses zero whitespace.
Before you rely on the result
- You've pasted the complete JSON, not a partial or truncated excerpt.
- If you got an error, you've checked for the specific issue mentioned (missing commas, unquoted keys, trailing commas) before assuming the tool is wrong.
- You've confirmed formatted and minified outputs represent the same underlying data, just styled differently.
- You've copied the specific output (formatted or minified) that matches what you actually need next.
Who this is for
- Developers debugging API responses by pretty-printing compressed JSON.
- Anyone minifying JSON config data for a field that requires single-line input.
- People validating hand-written or AI-generated JSON snippets for syntax errors.
- Anyone cleaning up JSON copied from documentation, chat, or another source before using it.
Real-world examples
Debugging a compressed API response
A developer pastes a single-line JSON API response into the tool and formats it, making the nested structure and field names much easier to read while debugging.
Minifying config for a size-limited field
Someone has readable, indented JSON configuration that needs to fit into a form field that only accepts a single line, so they minify it before pasting.
Catching a syntax error before deploying
A developer pastes a JSON config file into the tool before deploying and catches a missing comma via the error message, fixing it before it causes a runtime failure.
Limitations
- Invalid JSON shows an error instead of a best-effort result — fix the syntax first.
Frequently asked questions
Why am I getting an error on JSON that looks fine to me?
Common invisible issues include trailing commas after the last item, single quotes instead of double quotes, or unquoted object keys — all valid in JavaScript object literals but not in strict JSON. Check the error message for a hint at the specific problem.
Does formatting or minifying change the actual data?
No — both operations only change whitespace and formatting; the underlying data structure and values are identical between the original, formatted, and minified versions (assuming valid input).
Can this tool fix invalid JSON automatically?
No — it reports the error so you can fix the syntax yourself, rather than guessing at what you might have intended, which could silently change your data's meaning.
What does the indent size setting do?
It controls how many spaces are used for each level of nesting when you click Format — common choices are 2 or 4 spaces; it has no effect when minifying.
🔒 Runs in your browser — nothing is uploaded. Results are for reference only; see the disclaimer. Last updated: 2026-08-25
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