simstudioai/sim

Sim is an open-source platform for building and running AI agents. An AI agent is a program that uses a language model to take instructions and carry out multi-step tasks, often by calling tools, looking things up, or talking to other services. Sim positions itself as a central place where you design agents, connect them to outside systems, and run a whole group of them as an agentic workforce. You build workflows visually on a canvas. You drag agents, tools, and blocks onto the canvas, draw connections between them, and run the whole flow. According to the README, Sim can connect to more than a thousand integrations and language models, so an agent built in Sim can plug into many different services. A built-in Copilot helps you build flows from natural language: you can ask it to generate new nodes, fix errors, and iterate on the flow without manually wiring everything yourself. Sim also supports vector databases, which are a way of storing documents so an AI agent can search them by meaning rather than by keyword. You upload your own documents into a knowledge store, and the agent answers questions grounded in that specific content rather than only what the underlying model knows. To try it, you can use the hosted version at sim.ai, or run it yourself. The simplest self-hosted option is an npx command that starts Sim on localhost, this needs Docker installed and running. There is also a Docker Compose setup where you clone the repository and bring the stack up directly. The README notes a system needs around 12GB of RAM, and ports 3000, 3002, and 5432 should be free. The codebase is primarily TypeScript.