Plasmic

Plasmic is an open-source visual editing and content platform for building websites and applications. It allows users to design custom UIs with a drag-and-drop builder, connect to various data sources and APIs, and integrate with existing codebases. The platform supports collaborative development and offers flexible deployment options.

Plasmic is a strong match for Retool's concept. It explicitly offers a visual builder with drag-and-drop functionality, extensive integrations with various data sources and APIs, and the ability to integrate with existing codebases for customization. It also provides enterprise-grade security features like SSO and fine-grained permissions, and flexible deployment options. Many 'other' features like version control, analytics, and prebuilt components are also clearly present.