A simple to use dichotomous key builder developed from freely available software is described. The builder interface is completely web-based, so creation and editing of keys can be done anywhere via standard web browsers, this makes it particularly useful for collaborative efforts. For the end-user several features not available to paper-based keys are implemented, including a summary display of the path-history and future choices. A simple image database is tied to the builder, allowing attachment of text-annotatable images to each couplet. The key tool is particularly useful for storing historically important dichotomous keys in a manner which extends their function. Electronic keys may be exported for use in print publications if needed. Examples from the Hymenoptera, from several ongoing projects and historically important works are provided.