A JSON formatter takes minified or unreadable JSON and pretty-prints it with consistent indentation. Here is how the leading free options compare on privacy, features, and usability.
Pros
Cons
Pros
Cons
Pros
Cons
Pros
Cons
For privacy-conscious use or working with sensitive JSON payloads, FormatGenie is the best choice — everything runs in your browser with no data leaving your machine. For power-users who need a full GUI tree editor, JSON Editor Online is worth the extra complexity.
Only if the tool processes JSON entirely in your browser (client-side). FormatGenie processes all data locally — nothing is ever sent to a server. Avoid tools that validate server-side if your JSON contains credentials or PII.
Most formatters will show an error and stop. FormatGenie includes a Repair & Format button that fixes common issues: trailing commas, JavaScript-style comments, unquoted keys, and single-quoted strings.
Formatting adds indentation and line breaks for readability. Validating checks whether the JSON is syntactically correct. FormatGenie does both — it only formats valid JSON and highlights the error location if the input is invalid.