Composer vs Zero Install

Composer manages dependencies for PHP projects, installing and updating the libraries each project declares. By default, it keeps those dependencies in a directory within the project, and it can also manage a global project. It resolves dependencies and supports lockfiles, workspaces, private registry authentication, and offline installation. Packagist is its default package source; custom Composer, version-control, and local-path repositories are also supported. Composer integrates with Fossil, Git, Mercurial, Perforce, and Subversion. It can be installed locally or as a system-wide executable on Windows, Linux, and macOS. The latest version requires PHP 7.2.5 or later; the 2.2.x LTS line supports PHP 5.3.2 and later. Its audit command checks installed packages for security advisories, abandoned packages, malware flags, and other dependency policies. Composer is free under the MIT license. Plugins and scripts can run with the user's permissions, so the project advises against running Composer as root with untrusted packages.

Zero Install has no write-up on Specifiction yet; its figures are above.