JSON Formatter & Validator
Format, minify and validate JSON in your browser without rewriting key order, duplicate keys or exact number text.
Format or validate JSON
ReadyFormatting without data rewriting
After syntax validation, Muft changes only insignificant whitespace outside strings. It does not deserialize and reserialize the value, so key order, duplicate object keys, number notation and integers larger than JavaScript’s safe range remain exactly as entered.
What validation means
Validation confirms JSON syntax only. It does not check a JSON Schema, API contract, required fields, value types expected by another system or whether duplicate keys are acceptable to the software that will consume the document.
How to use it
Paste JSON, choose two spaces, four spaces or tabs, then select Format. Use Minify to remove insignificant whitespace or Validate to check syntax without changing the text. Copy the result when ready.
Privacy
JSON processing happens entirely in your browser. Content entered here is not submitted to or stored by Muft. Avoid pasting production secrets into any tool on an untrusted device.
Tool behavior last checked Aug 9, 2026.