appimage-builder was created to ease the packaging process of GNU/Linux applications. Originally it introduced a new kind of bundles that had as main characteristic the inclusion of a glibc copy. These bundles could be built on modern system and still be backward compatible. This flexibility is possible at a price of ~30mb.

In some scenario may not be desired therefore with the v0.9.0 release of appimage-builder is possible to create classic AppImage bundles without glibc but keeping the AppRun and its benefits.

In order to make a non-backward compatible bundle (the classic ones) you just have to exclude the opt/libc folder in your recipe as follows:

AppDir:
  files:
    exclude:
      # exclude glibc for a smaller but non backward compatible bundles
      - opt/libc

You may be wondering when should I prefer the classic format over the backward compatible one?

The backward compatible format eases considerably the packaging process. You can use the very latest binaries (or the ones shipped in your favorite distro) but you have to pay 30mb more. If you’re packaging a small utility with few dependencies, and those are available (or can be built on an old system) then use a classic bundle. Otherwise stick with the appimage-builder style.

You can check the appimage-builder documentation for more information about the tool.