The GOBL Builder is a fantastic starting point for learning about how to use GOBL and testing out your documents. Follow the link and try some of the features.

You can checkout the source code of the GOBL builder and even use this tool inside your own projects.

Behind the scenes, the builder uses the GOBL CLI compiled using the new WASM (web assembly) frameworks for Go, so there is no server-side logic, and no data leaves your browser.