JSON Formatter & Validator
Make a compact JSON payload readable and identify invalid syntax.
Maximum 500,000 characters. Use synthetic examples instead of secrets.
Local processing · No account · Input is not uploaded by this tool
How to use this tool
- Choose the relevant options. Set the operation, format or algorithm before running. The options above define how the result is interpreted.
- Enter data or load an example. {"name":"Alex","items":[1,2],"active":true}
- Run and inspect the feedback. Use the primary action, then read the status message. An error clears old output so it cannot be mistaken for a fresh result.
- Copy, download or start again. Copy and Download become available when a current nonempty result exists. Reset clears the text result; no input is stored by this site.
How it works
JSON.parse validates the text; JSON.stringify emits the selected indentation. Optional recursive key sorting helps human review, but integer-like key order follows JavaScript enumeration.
The computation is performed by this page’s JavaScript after you choose Run. Input and results are kept in the current tab’s memory. There is no background submission, analytics event containing your input, or server-side conversion in this build.
Practical example
Use Load example to try the supported format, then change one value and run again. Comparing those two results is a quick way to understand what the operation changes and what it preserves. The linked guides below provide worked examples for the edge cases relevant to this utility.
Common mistakes
Single quotes, comments and trailing commas are not strict JSON. Do not format a signed payload and expect its signature to remain valid.
Limits and unsupported tasks
This is not JSON Schema validation or lossless numeric parsing. Large numeric IDs can round, duplicate keys collapse to the last value, and original byte spelling is not preserved. Use at most 500,000 input characters.
Privacy and handling sensitive data
API payloads can contain session tokens, customer records and hidden nested credentials. Use a reduced synthetic payload when reproducing a problem. JSON input and the formatted result remain in tab memory; no conversion request is made. Copy and Download use your device. Browser extensions and hosting logs have separate boundaries, explained in the privacy policy.
Usage guides
- Format JSON without accidentally changing your data
- Fix common JSON syntax errors with a small debugging loop
- JSON numbers, large IDs and JavaScript precision
- JSON vs JavaScript object literals: what can cross the boundary?
- JSON minification vs HTTP compression: choose the right optimization
- A practical JSON API debugging workflow
Questions, answered
Does the JSON Formatter & Validator upload my input?
No. The implementation processes it in your browser and does not submit it to a server. Ordinary page requests still reach the hosting service.
Why did Copy or Download become unavailable?
The input changed or validation failed, so the previous output was cleared. Run the tool again to create a current result.
Can I use this for every production workflow?
This is not JSON Schema validation or lossless numeric parsing. Large numeric IDs can round, duplicate keys collapse to the last value, and original byte spelling is not preserved. Use at most 500,000 input characters.