Sim is the collaborative workspace for building, deploying, and monitoring AI agents and workflows — a visual canvas where you connect models, tools, and logic without writing glue code.
Sim is an open-source project on GitHub with around 30,000 stars, actively developed in 2026, and used by more than 100,000 builders according to the project. You design agentic workflows on a drag-and-drop canvas: LLM blocks for models from OpenAI, Anthropic, Gemini, and DeepSeek; tool and API integrations; knowledge and RAG components; and control flow for branching and loops. Workflows can be run interactively, deployed as APIs or chatbots, scheduled, and monitored from one workspace, with team collaboration built in.
To speed up adoption, Sim ships a library of templates for common patterns — research agents, support bots, document processors, lead enrichment — that teams can clone and adapt instead of starting from a blank canvas. Every workflow run is logged with inputs, outputs, and costs, so behaviour can be audited and improved over time, and an in-builder copilot helps assemble blocks using natural language.
Sim is freemium. The open-source version is free to self-host, and Sim’s hosted cloud offers a free starting tier with paid plans that add higher usage limits, team workspaces, and managed infrastructure.
Product teams, startups, and automation-minded builders who want to prototype and ship agent workflows visually — and prefer an open-source platform they can later self-host over a closed no-code tool.