GitLab Duo is GitLab’s AI feature set bolted onto the DevOps platform — code completion, chat, merge request summaries, vulnerability explanations, root-cause analysis for failing CI jobs, and test generation. It’s the direct analogue of GitHub Copilot + Copilot Chat, scoped to GitLab’s project, issue, MR, pipeline, and security-finding context.
Under the hood, Duo is a set of features that call out to an “AI Gateway” service that GitLab operates, which in turn proxies to underlying foundation models (historically Anthropic Claude for chat and Google Vertex AI models for code completion, with the set evolving). The gateway is what lets self-managed GitLab instances use Duo without shipping raw code straight to a third-party inference provider — requests go from the GitLab instance to GitLab’s gateway and back. Completion is wired into the Web IDE and several editor extensions (VS Code, JetBrains, Neovim) via the GitLab Language Server.
Duo is sold as an add-on on top of Premium/Ultimate tiers, split into Duo Pro (code suggestions + chat) and Duo Enterprise (plus the deeper MR/pipeline/vulnerability features and self-hosted model options). The differentiator versus Copilot is context: because GitLab already owns the MR, pipeline, and SAST data, Duo can answer questions like “why did this pipeline fail” or “explain this vulnerability in the context of this MR” without a separate integration layer. The flip side is that it’s only useful if you’re already on GitLab.