The large diversity of neuron types of the brain, characterized by a unique set of electrophysiological characteristics, provides the means by which cortical circuits perform complex operations. To quantify, compare, and visualize the functional features of single neurons, we have developed the open-source framework, CellExplorer. It consists of three components: a processing module that calculates standardized physiological metrics, performs neuron type classification and detects putative monosynaptic connections, a flexible data structure, and a powerful graphical interface. The graphical interface makes it possible to explore any combination of pre-computed features at the speed of a mouse click. The CellExplorer framework allows users to process and relate their data to a growing collection of “ground truth” neurons from different genetic lines, as well as to tens of thousands of single neurons collected across our labs. We believe CellExplorer will accelerate the linking of physiological properties of single neurons in the intact brain to genetically identified types.