Etch is a next generation builder currently under active development and available for early adopter testing. The approach with Etch is to first build a tool for advanced users that leverages the core web languages and only after it works well for advanced users would the easy mode be added. This was the opposite of most other builders, which started by targeting beginners and end up making site building more difficult for advanced users. The approach with Etch is to not hide the HTML and CSS technologies being used to create a web page but to provide an interface for using them. Etch is meant to be interoperable with Gutenberg so that you will be able to save as Gutenberg blocks or open pages created in Etch in Gutenberg.
You are able to use the Etch UI, write code, or do both. It is designed as a “unified” builder so that users can accomplish many common tasks without needing to leave the Etch interface. It includes features such as the ability to create and manage Custom Post Types and custom fields. Development of this new builder is currently proceeding ahead of schedule.
The features tagged here are available for testing in the beta version.