JSON Formatter & Validator
Format, beautify, validate and minify JSON online. Find syntax errors instantly and make JSON readable. Free, and your data never leaves your browser.
Size 0 BNodes 0
Your JSON is processed in your browser and never sent to our servers, so it's safe for internal API logs, customer data and private configuration.
About this tool
Paste raw JSON into this formatter and it validates the syntax as you type, then prettifies it with clean two-space indentation or minifies it down to a single transmission-ready line. Backend developers untangling API responses and DevOps engineers auditing config files reach for it whenever a payload turns to soup.
How to Format and Validate JSON
- 1
Paste your JSON into the input pane — a minified API response, a config file, a log fragment. Validation runs immediately, and the header reports the payload's size and total node count.
- 2
If the syntax is broken, the parser's error message appears with the failure details; fix the input until the error banner clears.
- 3
Click Prettify for readable, two-space-indented output or Minify to strip every non-essential character, then copy the result to your clipboard or download it as a .json file.
Why Format JSON with Wrklyst
- Safe for Secrets
- Parsing uses your browser's own JSON engine — tokens, API keys, and production payloads never cross the network, so nothing sensitive can land in someone's server logs.
- As Fast as JSON.parse
- Validation is native browser code running locally, so a multi-megabyte payload formats in the time a remote tool would still spend uploading it.
- Nothing Between You and the Output
- No sign-up gate, no daily conversion allowance, no interstitials interrupting the workflow — the formatter is simply there when a payload needs untangling.
Pro Tips for Working with JSON
- Three mistakes cause most validation failures: a trailing comma after the last item, single quotes, and an unquoted key — check those first.
- Minify configs before storing them in environment variables; stray newlines are the classic cause of "works locally, breaks in deploy".
- The node count in the header is a quick sanity check — if an API response suddenly reports far fewer nodes than yesterday, the payload changed shape.
- Validate hand-edited JSON here before restarting the service that consumes it; a ten-second paste beats a failed deploy.
Frequently asked questions
How do I find where my JSON is broken?
The moment the input fails to parse, the engine's exact error appears — typically naming the unexpected character and its position, like "Unexpected token } in JSON at position 412". Work outward from that position; the true mistake, often a missing comma, usually sits just before the character the parser choked on.
What's the difference between Prettify and Minify?
Prettify re-renders the data with two-space indentation and one key per line, built for human eyes during debugging and code review. Minify strips all whitespace into one continuous line, shrinking the byte count for network transmission, environment variables, or embedding JSON inside another string.
Why does valid JavaScript fail validation here?
JSON is stricter than a JavaScript object literal. Single quotes, unquoted keys, trailing commas, comments, and undefined are all legal in JS but forbidden in JSON. If you copied an object out of source code, switch to double quotes and drop trailing commas before it will validate.
How large a JSON file can it handle?
There's no artificial cap — capacity is bounded only by your browser's memory, and multi-megabyte API dumps format fine on a modern machine. For very large files, prefer Minify when possible: indentation can triple the character count, and rendering tens of millions of characters is what actually slows a tab down.