JSON Formatter & Minifier
Format, validate and minify JSON instantly with inline error highlighting. No data leaves your browser.
Malformed JSON from an API response, a config file, or a copy-pasted log line can be maddening to debug by eye. This JSON Formatter & Minifier instantly validates your JSON as you type, pinpoints exactly which line and column an error occurs on, and lets you pretty-print or minify with a single click.
It's built for the quick, repeated checks developers do dozens of times a day — no need to open a separate app or paste sensitive payloads into a website you don't control.
How to use the JSON Formatter
- 1
Paste or type your JSON
Paste JSON directly into the editor, or start typing from scratch — validation runs continuously in the background.
- 2
Watch the live status
A green 'Valid JSON' badge confirms well-formed input; an error banner appears immediately if something's wrong.
- 3
Read the error location
Invalid JSON shows the exact line and column of the problem, taken directly from the parser's error position, so you don't have to hunt through the whole document.
- 4
Format for readability
Click Format to pretty-print the JSON with your chosen indent size (2 spaces, 4 spaces, or compact).
- 5
Minify for transport
Click Minify to strip all whitespace and produce the smallest possible representation, ideal for pasting into config files or request bodies.
- 6
Copy or download
Use Copy to grab the current text to your clipboard, or Download to save it as a standalone .json file.
Why convert in your browser instead of uploading to a server?
Sensitive payloads stay local
API responses and config files often contain tokens, internal URLs, or customer data. Because parsing and formatting happen with the browser's native JSON.parse and JSON.stringify, nothing is ever sent to a remote endpoint.
No size limit on pasted JSON
Web-based formatters that proxy through a server commonly cap request size. Local parsing is limited only by your browser's memory, so multi-megabyte payloads work fine.
Instant validation on every keystroke
There's no Validate button to click and wait on — the parser re-checks your input the moment you stop typing, with zero network latency.
Works completely offline
Once the page has loaded, formatting and minifying JSON require no internet connection at all.
Frequently asked questions
How does the tool find the exact error location?+
It reads the character position reported by the browser's native JSON.parse() error message and converts it into a line and column number by counting newlines up to that point in your text.
What's the difference between Format and Minify?+
Format re-indents your JSON with line breaks and spacing for human readability. Minify strips all unnecessary whitespace to produce the smallest possible byte size, typically used when embedding JSON in a URL or config.
Does this tool validate against a JSON Schema?+
No — it validates that your input is syntactically well-formed JSON per the JSON specification, not that it matches a particular schema or shape.
Can I format very large JSON files?+
Yes, within the limits of your browser's memory — there's no artificial cap imposed by the tool. Very large files (tens of megabytes) may feel slower simply because the parser has more to process.
Do trailing commas or comments break the validator?+
Yes — this tool follows the strict JSON specification, which doesn't allow trailing commas or comments. If you're working with JSON5 or JSONC, those extensions will show as invalid here.
Is my JSON saved anywhere after I close the tab?+
No. Everything lives only in the browser tab's memory for the duration of your session — closing or refreshing the page clears it completely.
Whether you're debugging a webhook payload, cleaning up a config file before a commit, or minifying a JSON blob for a URL parameter, having instant, local validation removes the friction of switching tools mid-task.
Keep this tab open alongside your editor or terminal — since there's no server round trip, it's often faster than shelling out to a command-line JSON tool.