Hello,
My name is Krzysiek. I work daily as a Web Developer, doing both backend and frontend for projects I work on, and I use Freelancer to work on small projects in my free time.
About the technologies, I have experience with Node.js, jQuery, Backbone.js, Cordova/PhoneGap, Ruby on Rails, Loopback, SQLite, PostgreSQL; in fact there's too much of them to write down.
If I have bid on your project I probably have been working on something similar to what you want to achieve, or I simply know how to do it. I never bid blindly, and Freelancer isn't my full-time job.