Cargo vs Composer

Cargo is the free package manager and build tool for Rust, used through a command-line interface. It downloads dependencies, builds packages, and supports repeatable builds with lockfiles. Developers can compile, check, document, test, run, package, install, and publish Rust projects. The `cargo new` command creates a package, defaulting to a binary; adding `--lib` creates a library. Cargo uses crates.io by default and also handles alternate registries, Git dependencies, and local paths. Workspaces allow multiple packages to share a lockfile and output directory. Package features can enable conditional compilation and optional dependencies. In offline mode, Cargo avoids network access and attempts to use cached data. It supports authentication options for registries and new subcommands without modifying Cargo itself. Rustup installs Cargo with the stable Rust release, and installation instructions cover Windows, macOS, Linux, and other Unix-like systems. Cargo is open source under the MIT and Apache License, Version 2.0. Some documented capabilities remain unstable and require a nightly toolchain and `-Z` flags.

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.