GitLab CI/CD is a continuous integration and delivery system that can be used to manage Terraform state files. It provides features such as pipeline configuration, runner distribution, job execution, artifact storage, and environment variable management. Using GitLab CI/CD for managing Terraform state offers benefits like version control, centralized repository, encryption, access control, collaboration, locking and unlocking states, and remote execution of commands. Spacelift is another platform that can manage Terraform state files with additional features such as OPA policy integration, self-service infrastructure, drift detection, and workflow automation.