Compress ZIP
Rebuild a ZIP archive with optimized compression and see exactly what you saved.
Drop your ZIP file here
or browse files from your computer or phone
How to use Compress ZIP
Drop an existing ZIP archive into the compressor.
Choose a recompression level: Fast, Balanced, or Maximum.
Click 'Compress ZIP' to rebuild the archive locally.
Review the original vs. compressed sizes and download if it helps.
Frequently asked questions
Why does my ZIP not get much smaller?
ZIP files often already contain compressed data (JPEG, PNG, MP4, PDF, Office documents). Recompressing those formats provides little or no benefit, which is why the tool reports honest results instead of promising savings.
What does the tool do with already-compressed formats?
Entries whose formats are already compressed are stored without re-encoding, so their bytes are never degraded or inflated.
What if the recompressed archive is larger?
The tool tells you. You are never forced to download a larger result.
Are my files uploaded during compression?
No. Recompression runs entirely on your device inside the browser.
Does compressing change my file contents?
No. File bytes are preserved exactly; only the way they are packaged in the archive changes.
More free ZIP tools
All tools process files locally in your browser memory. Zero uploads.