Ecosia is the search engine that plants trees with its ad revenue. Get the free browser extension and use Ecosia every time you search.
The international team is based in Berlin, Germany. They  publish their monthly financial reports and tree planting receipts as a way to can keep them accountable as they journey to a reforest world, but looking at their progress, it’s hard not to trust them!
Since 2009, they have supported 25,000 farmers on the ground worldwide, restored 20,000 hectares (49k acres) of land and planted 170 different tree species worldwide.

Change your default browser to them to help on their ambitious journey to one billion trees by 2020.