Not only is it tiny (5 megabytes for the base image), it has a tool, apk which allows small versions of pretty much any Linux development environment to be installed.
I have a local ISO image with tarballs for both ARM 64-bit and X86 64-bit with most of the root filesystem for a working Linux system, such as what one can overlay over a Busybox Docker image. Directions for overlaying this tarball to make a functional 3.14 version of Alpine Linux in Docker are included.
The reason I have this particular version of Alpine Linux is because Alpine Linux is the standard testing environment for the 3.4 branch of MaraDNS, which is only updated for security and other important updates.
This ISO image has, as required by the large number of copyleft packages in the tarball, source code.
I also have a local copy of the patch package for Alpine 3.14, with both ARM64 and 64-bit X86 binaries, as well as full source code.
There are also GPG sig files signed with the MaraDNS signing key.