Google Jules

GStack is an open-source Claude Code workflow system created by Y Combinator CEO Garry Tan, designed to encode specialized AI roles for planning, code review, QA, and shipping. Built with Bun and Playwright, it uses route-aware QA and structured release workflows to connect code changes with actual application behavior. Enables developers to achieve 10,000+ lines of quality code per week.

Kilo Code is an open-source AI coding agent for VS Code, JetBrains, and CLI that generates code from natural language, automates complex tasks, and runs terminal commands. It supports 500+ AI models at provider rates and features an Orchestrator mode that breaks complex tasks into coordinated subtasks across planner, coder, and reviewer agents. With 1.5M+ users and 25T+ tokens processed, it's the #1 coding agent on OpenRouter.

Cursor Composer 2 is an advanced agentic coding model built into the Cursor IDE, released March 19, 2026. With a 200,000-token context window, it autonomously plans and executes complex, multi-file coding tasks across an entire codebase — handling file edits, terminal operations, and tool use at frontier-level performance. It is used by over 50,000 businesses including Stripe.

StepFun's open-weight LLM released early February 2026. Part of the Step series known for strong reasoning and coding capabilities. Competitive pricing with fast inference speeds. Good for developers seeking open-source alternatives for general AI tasks.

Goose is an open-source AI coding agent developed by Block (formerly Square) that performs multi-step software tasks autonomously in your terminal. It supports any LLM provider — including Claude, Codex, and Gemini via ACP (Agent Client Protocol) — and offers macOS sandboxing, MCP extension support, and a rich CLI for automated development workflows.

Agentation turns UI annotations into structured context that AI coding agents can understand and act on. Click any element on your screen, add a note, and paste the output directly into Claude Code, Codex, or any AI coding tool to fix UI bugs faster. It bridges the gap between visual feedback and actionable AI instructions.