Free online JSON size analyzer. Measure character count, byte size, nesting depth, key count and compression ratio. Runs locally in your browser, no data uploaded.
100% Local
How to Use the JSON Size Analyzer
Paste JSON into the input box. Click Analyze Size to get a full report: original and formatted character and byte counts, minified size, compression ratio, line count, max nesting depth and total key count. Use Clear to reset.
What the analyzer measures
Character and byte counts for original, formatted and minified versions
Compression ratio — how much smaller minified JSON is
Maximum nesting depth of the object tree
Total number of keys and array elements
Features
Instant analysis — no upload, no wait
Handles large JSON payloads without performance issues
Byte counts use the browser's native Blob API
All processing runs locally in your browser. Your data is not uploaded to any server.