JSON Formatter & Validator
Pretty-print, minify and validate JSON. Jump-to-error highlighting, configurable indent, handles nested structures up to any depth.
Last updated: April 2026 · Runs in your browser · No sign-up
Format vs minify
Formatting (pretty-printing) adds indentation and newlines so a human can read the structure. Minifying strips all optional whitespace to shrink payload size — useful for embedding JSON in URLs or reducing API response bandwidth.
Common gotchas
- JSON keys must be double-quoted strings — no bare identifiers.
- JSON has no comments — use JSONC or strip them before parsing.
- Numbers can't have leading zeros or trailing decimals.
- undefined and Infinity aren't valid JSON values.
Frequently Asked Questions
What JSON errors does it catch?
Trailing commas, unquoted keys, single quotes instead of double, unterminated strings, and deeper structural problems. The error message points to the exact line and column.
Does it support JSON5 or JSONC?
Strict JSON only by default (per RFC 8259). Toggle 'relaxed mode' to accept JSONC comments and JSON5 features like trailing commas and single-quoted strings.
Can I sort keys alphabetically?
Yes. Sorting keys is useful for diffing two JSON files or making object order deterministic before hashing.
Is the data sent to a server?
No. Parsing, formatting and validation happen entirely in your browser. Paste sensitive payloads without concern.