A connectome is the wiring diagram of connections in a nervous system. Mapping this network of connections is necessary for discovering the underlying architecture of the brain and investigating the physical underpinning of cognition, intelligence, and consciousness [1, 2, 3]. It is also an important step in understanding how connectivity patterns are altered by mental illnesses, learning disorders, and age related changes in the brain. Fully automatic computer vision techniques are available to segment electron microscopy (EM) connectome data. Currently we use the Rhoana pipeline to process images, but results are still far from perfect and require additional human annotation to produce an accurate connectivity map [4]. Here we present Mojo 2.0, an open source, interactive, scalable annotation tool to correct errors in automatic segmentation results.