Draw.io

Diagrams.net (previously known as Draw.io) is a professional, open source diagramming with online or desktop application without registration.

FAQ

How to import Lucidchart diagrams into draw.io?

https://desk.draw.io/support/solutions/articles/16000063693-how-to-import-lucidchart-diagrams-into-draw-io

How to add a template to an additional page in the existing diagram?

https://desk.draw.io/support/solutions/articles/16000088435-how-to-add-a-template-to-an-additional-page-in-the-existing-diagram-

How to use Layers?

https://desk.draw.io/support/solutions/articles/16000067815-how-to-use-layers-

Interactive diagrams with custom links and actions

https://about.draw.io/interactive-diagrams-with-custom-links-and-actions/