Compress ZIP Files Online

Yes — compressing ZIP archives is free, with no signup and no watermarks. Files are deleted automatically within 24 hours.

It depends on how the archive was made. Many ZIPs — especially ones produced by export features, backups and some operating systems — store files with little or no compression, and those can shrink by half or more when re-packed at maximum level. An archive that was already tightly deflated has little left to give, and a ZIP full of JPEGs or videos barely moves because that data is already compressed. We analyze your archive and show you the estimate before you commit.

No. ZIP compression is lossless at every level: each file is re-packed byte-for-byte identical, and every folder path is preserved exactly. Only the container gets smaller — nothing inside is recompressed into a different format or reduced in quality.

Not while it is protected. An encrypted archive cannot be re-packed without its password, so we detect that up front and tell you clearly instead of failing halfway through. Remove the password first, then compress.

Files travel over an encrypted connection, are processed on our servers, and are permanently deleted within 24 hours. We never open your archive beyond reading its file table, never extract it to disk, and reject malformed archives — including zip bombs and unsafe file paths — before processing starts.

ZIP uses the Deflate algorithm, which trades time for size across levels 1–9. Level 9 produces the smallest archive Deflate can make but takes the longest; the Balanced default reaches nearly the same size in a fraction of the time. Level 0 stores files without compression, which some workflows want for speed. The Custom preset gives you the exact level.