FREE FOSS
AdAway is an open source ad blocker for Android using the hosts file and local VPN. AdAway allows users to easily add their own sources of hosts files and even support for a blacklist/whitelist!
AdAway is not available on Google Play! It was removed by Google due to Violation of section 4.4 of the Developer Distribution Agreement.
AdAway is fully open and licensed under GPLv3+.