GitHub Copilot is the AI coding assistant that defined the category. Launched in 2021 as a collaboration between GitHub and OpenAI, it started as a single-purpose autocomplete tool that suggested code as you typed. Four years later, it has transformed into something far more ambitious: a multi-model, agentic coding platform that reaches across your entire development workflow — from inline completions in your editor to autonomous agents that turn GitHub issues into reviewed pull requests while you sleep.
The inline completions remain Copilot's bread and butter, and they are still the fastest and most accurate in the industry. Suggestions appear almost instantly, often before you finish typing a function signature. The acceptance rate is high because the model has been trained on an enormous corpus of code and benefits from deep integration with the GitHub ecosystem. For many developers, these completions alone justify the subscription — the small time savings on each suggestion compound into hours saved per week.
Multi-model support arrived as one of the most significant additions. Developers can now switch between models from OpenAI, Anthropic, and Google directly within Copilot Chat, matching the model to the task at hand. Claude for nuanced reasoning about complex architecture, GPT for speed on routine questions, Gemini for its large context window — having model choice within your existing workflow means you do not need to switch tools to access different AI capabilities. This is a meaningful advantage over AI-first editors that lock you into a single provider.
Agent mode represents Copilot's push into agentic development. Unlike traditional chat or inline edits, agent mode can independently translate ideas into code, identifying necessary subtasks and executing them across multiple files. It runs terminal commands, fixes lint errors, and iterates autonomously until the task is complete. For straightforward tasks — adding error handling to all API endpoints, creating tests for a module, refactoring a function — agent mode works well enough that you do not need a separate tool. However, complex multi-file refactoring involving ten or more files with architectural implications is where Cursor and Claude Code still pull ahead. Copilot's agent tends to make more mistakes on tasks at that scale.
The coding agent is perhaps the most forward-looking feature. You can assign a GitHub issue directly to Copilot, and it will work in the background — spinning up a secure development environment powered by GitHub Actions, making the required changes, running tests, performing its own code review, and opening a pull request for you to review. For well-scoped, single-component tasks, this works reliably. It excels at bug fixes, test additions, documentation improvements, and small feature implementations. The agent even runs code scanning, secret scanning, and dependency vulnerability checks before opening the PR, catching security issues before they reach human review.
IDE support is unmatched in the industry. Copilot works natively in VS Code, Visual Studio, JetBrains IDEs, Eclipse, Xcode, and Neovim. Agent mode has expanded beyond VS Code into JetBrains, Eclipse, and Xcode as well. No competing tool comes close to this breadth. For teams with mixed editor preferences — frontend developers in VS Code, backend engineers in IntelliJ, mobile developers in Xcode — Copilot is the only AI assistant that works across the entire team without compromise.