Run DEFLATE levels 1, 3, 6, and 9 on your files and see size vs time trade-offs side-by-side. Find the sweet spot for your data, runtime, and bandwidth budget.
Per-job file size, entry count, and batch caps for Level Optimizer. Limits apply to every Archive tool in JAD Apps; upgrade for larger uploads and bigger batches.
| Tier | Max archive size | Max entries / archive | Max files per batch |
|---|---|---|---|
| Free | 47.7 MB | 500 | 1 |
| Pro | 476.8 MB | 50,000 | 20 |
| Developer | 1.86 GB | 50,000 | 20 |
This tool requires the Pro plan or higher.
Drop the file or files you want to benchmark
fflate compresses with levels 1, 3, 6, and 9, timing each pass with performance.now()
Read the JSON metrics table and chart — pick the level that matches your priorities
0 bytes uploaded. Compression Level Optimizer runs entirely in your browser using fflate, zip.js, and libarchive WASM. Your archive files never leave your device.
Level 1 is fastest with weakest compression; level 9 is slowest with the best ratio. Level 6 is the universal sweet spot — typically within 5% of level 9 size at 30% of the time.
No. Text and source code compress to 15–25% of original; binary executables 60–80%; already-compressed media (JPEG, MP4, MP3) barely shrink and may even grow due to ZIP header overhead.
Yes — after running the comparison you get a download for the smallest ZIP automatically. The metrics report tells you which level produced it and at what time cost.
Drop files and get a perfectly compressed ZIP with the optimal speed/size trade-off. Powered by fflate level 6 — the universal sweet spot. Zero upload.
Open toolInspect every entry in a ZIP and see compression ratios per file plus the overall archive ratio. Spot already-compressed files that don't benefit from re-zipping.
Open toolDrop a folder of archives and get a unified report: format, total size, compressed size, entry count, ratio, largest file. Perfect for backup audits.
Open tool