Typically 10–30% for hand-formatted JSON, depending on nesting depth and how much indentation was present. Deeply nested documents save the most because every level adds leading whitespace to every line. The savings figure above the output shows the exact number for your input.
Should I minify JSON if my server already uses gzip?
The marginal gain is small. Gzip and Brotli compress repeated whitespace extremely well, so a minified and a formatted document often land within a few percent of each other on the wire. Minifying is still worth it for data stored uncompressed — database columns, localStorage, embedded config — and for reducing parse time on very large payloads.
Is minified JSON still valid JSON?
Yes. Whitespace between tokens is insignificant in JSON, so a minified document is exactly as valid as a formatted one and every parser accepts it. This tool parses your input before re-serialising it, so invalid JSON is rejected rather than silently compressed.