Format, query & visualize
Pretty-print, validate, repair, sort, run JSONPath and explore data as a collapsible tree or mind map.
Private JSON workspace
JSON formatter & validator
Pretty-print, validate, minify, repair and compare JSON in your browser. Convert JSON to XML, CSV, YAML or TOML without sending data to a server.
JSON formatter
Input
Output · preview.json
{ }
Run a tool to see a polished result here
Free online JSON formatter, validator and converter
JFmt is a free JSON formatter, JSON beautifier and JSON validator that runs entirely in your tab. Paste a payload to pretty-print it, check that it is valid JSON, minify it for production, repair common syntax errors, or convert JSON to XML, CSV, YAML, TOML, query strings and Postman collections. Processing stays on your device.
34 local tools
A focused toolkit for real JSON work.
Useful operations, clear errors and responsive performance without accounts, uploads or distractions.
Convert every common format
Move between JSON, CSV, XML, YAML, TOML, query strings and Postman collections without uploading data.
Generate production models
Turn JSON and SQL into portable SQL, Java, C#, Go and Dart model definitions in one click.
Built for privacy
No upload. No account. No history.
Formatting runs inside a dedicated browser Web Worker. Content is not posted to JFmt, written to cookies or saved unless you enable auto-save.
What is an online JSON formatter?
A JSON formatter (also called a JSON beautifier) indents objects and arrays so a payload is readable. JFmt also validates JSON syntax, minifies for APIs, and repairs issues such as trailing commas or single quotes.
Can I convert JSON to XML, CSV or YAML?
Yes. Conversion is local in the same tab: JSON with XML, CSV, YAML, TOML, query strings and Postman collections. Nothing is posted to jfmt.dev.
Can I format sensitive JSON?
Processing is local, but you should still remove secrets before sharing screenshots or copied output with other services.
Does it support large files?
The Web Worker keeps parsing away from the interface. Practical limits still depend on your browser and device memory.
What does repair change?
Repair targets syntax, not meaning. Always review repaired output before using it in production systems.