There are a lot of such tools which allow to create a layout of your pages. In case of builder you should consider page as a desk for combining components into some composition which you will reuse as a component itself.
So, there is very small similarity - only because you can copy/paste/delete some components.
Your tool looks awesome! Yes there are lots of such tools.I should have worded mine as 'something along the lines of ...' instead of saying that its similar.