To distribute binary packages we use a number of different ways, depending on how large the images are. For smaller images, like firmware and client installs, we use GitHub's releases. For larger downloads, like the VM and Raspberry Pi images, we use a combination of our own servers, torrent and Mega.
All tools we use for firmware/software/electronics design is open source and freely available (except tools for iOS). For a list of tools and links to their sites have a look at the tools page. Most of these tools are pre-installed and ready to use in our virtual machine.
Since a while back now we have moved all our source code to GitHub. There's a lot of repositories since every piece of software has it's own repository. For example the Crazyflie 2.0 firmware is distributed in 5 different repositories (nRF51 mbs, nrf51 bootloader, nRF51 firmware, STM32F4 bootloader, STM32F4 firmware).