You fill the form they have on their website and submit a 60 seconds video telling why you want to work with them and what you can bring to the team

– Received an email because of my contributions on StackOverflow, they clearly stated that they are looking for a web developer to work for 2.5 months. – They asked me for work references, I provided GitHub projects and anonymous description of my recent works. – Got introduced to the CEO and the CTO and they asked me to work in a internal tool along with the CTO to measure my web development experience (got paid for that). – Signed a contract... and I'm still working with them since 2014.