| Autoload |
| CaBundle |
| Command |
| Config |
| Console |
| DependencyResolver |
| Downloader |
| EventDispatcher |
| Exception |
| Installer |
| IO |
| Json |
| Package |
| Plugin |
| Question |
| Repository |
| Script |
| SelfUpdate |
| Semver |
| Spdx |
| Util |
| XdebugHandler |
| Cache | Reads/writes to a filesystem cache |
| Compiler | The Compiler class compiles composer into a phar |
| Composer | |
| Config | |
| Factory | Creates a configured instance of composer. |
| Installer | |
| XdebugHandler |