Dify

An open source platform to put together chatbots, RAG pipelines and agentic workflows from a visual interface, with support for many models and deployment in their cloud, in your VPC or self-hosted. For an agency the value is handing the client something they can operate without writing code. Two things to check first: its license has commercial conditions and is not clean Apache, and self-hosting adds a piece of infrastructure that someone has to maintain.