Very impressive, thanks for sharing! I'm more interested in how you grew the user base plus any other growth hack tips you might have? There is the obvious free SEO and social media publicities, but it's always tricky to get engaged users.
I would say I got lucky. I started the site not too long after the public launch of Bootstrap. And after about two weeks of farming Bootstrap sites myself (to build up content) I submitted it to HN. Then it went nuts. I got a spot on the official docs homepage without even asking and rode the wave as Bootstrap soared to becoming the most popular frontend framework and Github repo.
The popularity this brought was untold as hundreds of sites started naturally linking to BWB. I guess being first was the most important thing here.
I've also made a point to make it always free and easy for folks to submit a site. There's no complex review process and no fee (if you don't mind waiting in line). This gets some loyal supporters who are happy to provide new content on a somewhat regular basis.
The knock-on effect has been that Google seems to love the site and now the majority of my visitors come from searches. This despite Tumblr not being the greatest base for SEO.
