neuron-catalog is a web-based database for small groups (e.g. a lab) collaborating on neuronal circuit mapping. It provides a simple platform to organize your notes about driver lines, neuron types, brain regions and putative connectivity. Each group that wants to run the neuron-catalog can run their own server, as the software is free and open source (GNU Affero General Public License v3). Because it is run as an isolated, standalone database, the neuron-catalog can be used as a collaborative lab-notebook to record novel observations during the process of discovery. Thus, neuron-catalog complements large-scale efforts which require extensive curation by providing a collaboration platform before the data are ready for integration into a finished dataset.