Buildkite emphasizes extensibility in CI/CD processes, allowing teams to tailor their workflows through plugins, which are self-contained functionalities that modify various job lifecycle stages. Plugins can be open-source or private and are managed directly in pipeline definitions, facilitating decentralization and version control. The platform's integration with HashiCorp Vault is particularly notable, with the Vault secrets plugin enabling secure management of sensitive information like API keys and passwords. This plugin allows agents to authenticate and acquire secrets during job execution, supporting multiple authentication methods and enhancing security through granular access policies. Buildkite's approach to plugins, written in Bash, ensures maintainability and reduces compatibility issues, and users can explore existing plugins or create custom solutions as needed.