are there any open source libraries for web builder

As a part of a project I am looking to create a web builder which will have a list of components and after drag and drop it will be rendered on the UI and the ability of download the code, though it is not as extensive like webflow tool, I have certain pre-defined components and user should be able to add them and arrange it in layout.

Since this is not the crux of the tool, I dont want to develop it from scratch and looking to use some existing open source libraries.

Also I am not sure what is the best approach or starting point for this.

Any comments welcome.