Gun.io

Best for: Freelance developers.

Tooltip: Requires an application and screening process.

Gun.io was borne by free and open source software developers who were seeking to build a new way of life - one where people can find quality work while also having the freedom to follow their own passions. Over 950 top companies, including Amazon, SolarCity and Zappos have used Gun.io to find talented developers. All developers are handpicked for experience, talent and professionalism.