Are you asking if there are competitors? Hard question to answer
because it depends on what you need. If you are looking at the full
vision of Maqetta (runs in cloud, open source, true WYSIWYG, creates
actual running web apps, supports arbitrary popular widget libraries,
integrated CSS theme support, desktop and mobile, web-based review/
commenting, wireframing, etc.), then as far as I know, we are the only
thing going with that particular set of ambitions.
Jon Ferraiolo