JAR and APK files are really ZIP, as is EPUB. True, ZIPs are hard to grep. However, gzip and progeny come bundled with convenience scripts as zgrep, bzgrep, xz

JAR and APK files are really ZIP, as is EPUB. True, ZIPs are hard to grep. However, gzip and progeny come bundled with convenience scripts as zgrep, bzgrep, xzgrep, etc. Maybe use a grep-friendly format if that's important to you, or otherwise a filesystem with transparent compression (btrfs, ZFS, or [gasp] NTFS).