DevOps platform company. Mentioned in Counterintuitive Rails pt. 1 as Ivan Nemytchenko's employer (European developer advocate) and referenced again in The Curse of Service Object — Ivan is now a former GitLab employee. GitLab's open-source Rails codebase is used as a source of real-world service-object examples: two-arm readers with caching, services inheriting from a custom BaseService framework, services calling other services, a 200-line service that began as two private methods and grew into a 'monster', plus widespread controller-responsibility leakage (session handling, response prep). GitLab is framed as a sophisticated application with complex login/security logic, and in Q&A as the kind of big app most people will never work on.