Starring at the source code, it seems that there is no support for deflate64: * https://github.com/gildas-lormeau/zip.js/blob/master/lib/core/constants.js#L31-L32 and * https://github.com/gildas-lormeau/zip.js/blob/master/lib/core/zip-reader.js#L416-L418 Would you consider adding minimal decompression support for `deflate64 `in the future ? References: * https://github.com/thejoshwolfe/yauzl/issues/58 * https://github.com/nih-at/libzip/issues/116 * https://pypi.org/project/zipfile-deflate64/