Our free ZIP Compressor re-evaluates existing ZIP archives and applies maximum level-9 DEFLATE compression to shrink file sizes. Re-pack source code repositories, document archives, and project backups in client memory to save disk space and meet email attachment size limits.
Select or drop an existing ZIP archive file into the uploader box.
Choose your target DEFLATE compression level (Level 9 for maximum size reduction).
Click "Compress ZIP" to re-encode the archive and download your smaller ZIP file.
Unpacks internal streams in memory and applies high-efficiency DEFLATE compression for tighter archive compaction.
Maintains exact internal folder hierarchies, sub-directories, and file metadata while reducing total byte size.
Re-compression routines execute entirely within client browser memory without external server transmissions.
Compression Levels (Fastest, Balanced & Maximum): Zip compression algorithms trade CPU processing time for file size reduction. Fastest Mode uses small LZ77 search windows for instant archiving, Balanced Mode provides optimal speed/size ratios, and Maximum Mode evaluates deep string matches to achieve maximum byte reduction.
Universal PKZIP Standard Compatibility: Compressed archives generated by BunchTool adhere strictly to PKZIP 2.04g spec standards. Archives open seamlessly across native operating system unzippers: Windows File Explorer, macOS Archive Utility, Linux unzip, iOS Files, and Android File Manager.
100% Private Local WebAssembly Compression: Binary encoding and file compression run strictly inside local web browser RAM tab memory. Proprietary codebases, photos, and confidential documents are compressed locally without uploading a single byte to remote servers.