dify

dify is an open-source platform for building agentic workflows and RAG pipelines with rich model and tool support, all in one collaborative workspace. It combines visual building with the escape hatch of custom code.

You can deploy it on cloud, in a VPC, or fully self-hosted, so teams move from prototype to production without rebuilding the stack. If you are assembling agents with real tool use and retrieval, it is one of the most complete open options.