It looks like Kiwix uses the ZIM file format, which appears to have diffing support [0] (see zimdiff and zimpatch). That said, it doesn't look like Kiwix actual

It looks like Kiwix uses the ZIM file format, which appears to have diffing support [0] (see zimdiff and zimpatch). That said, it doesn't look like Kiwix actually publishes those diffs. [0] https://github.com/openzim/zim-tools/tree/master/src https://github.com/openzim/zim-tools/tree/master/src