Emdash is an open-source agentic development environment delivered as a desktop application. It lets engineering teams develop software faster by running multiple coding agents in parallel, supporting 20+ agent providers including Claude Code, Codex, and Gemini. Emdash uses git worktree isolation so agents can run simultaneously without conflicting with one another. It was founded in 2025 and is a Y Combinator Winter 2026 company based in San Francisco.