A ZIP that "cannot be opened" almost always has a damaged central directory or a bad entry — the map of the archive is broken even though the compressed files inside are still there. zip.repair rebuilds the archive from its raw entries and recovers every readable file into a fresh, valid .zip. Free, online, no watermark.
Why ZIP files get corrupted
ZIP archives corrupt from interrupted downloads, failed transfers, or a damaged central directory. Because each file is stored with its own local header, the contents can be recovered by scanning those entries even when the directory at the end is unreadable.
What repair can and can't recover
Repair works well for interrupted downloads, broken headers or indexes, and files that open in one program but not another. Files whose compressed data is itself missing can't be restored, but everything still readable is recovered.
Recover individual files
Even when the archive as a whole is broken, the files inside are usually intact. The rebuild extracts every entry it can read into a fresh, valid ZIP you can open normally.