I'm working on www.seeflo.com
It still has some glitches but the start of the application is there.
My biggest problem right now is finding my audience.
First load of your page took a very long time for me. I think you'll have a very high bounce rate until you get your static page load times under control.
According to the first site testing tool I found (https://www.dotcom-tools.com/website-speed-test.aspx), there's a clear delay when accessing from outside Europe or Canada. Less than 2s to Frankfurt and London, but 5-6 for the US and 11+ to Australia.
I looked into it.
Gzip compression was off, even though it was configured in nginx.
Highlightjs was included in my main javascript, while I only need it for the instructions to highlight some html/js/ruby/php. It's a whopping 100kb by itself.
I moved this to the instructions page, and I'm using cloudfront now as a CDN.