Georeferencing preserved specimens represents a major effort at the Museu de Ciències Naturals de Barcelona (MCNB), given the available resources and limited staff that can be allocated to the task. Georeferencing is a labour-intensive and hard-to-automate task that requires software tools that can help in making it as efficient as possible. The tool we present, Ali-Bey, has been slowly developed over 15 years and its functionalities have been gradually built in a process of development, testing, use in production and refinement, rather than as a single development cycle out of a comprehensive specifications requirement document. At the start, the MCNB could not find a tool that fully satisfied the requirements listed as essential and made the decision to develop a custom tool. At the end, the initiative has proved successful since it has delivered a new georeferencing tool that meets the MCNB's needs, all in a context of yearly scarce availability of funds. The tool has been gradually matured and developed over the years, in line with the scarce financing. Only recently, after reaching a notable set of novel features, we considered to release it as an open-source project. The MCNB has supported its development up until this date and decided to open it in order to give the NHC community the opportunity to contribute to its development. We present the software tool Ali-Bey that provides new functionality for the georeferencing of specimens in Natural History Collections, namely the possibility of cooperation between different institutions, the traceability of georeferences and the capability of managing different versions of a same site name, namely for historical reasons. The tool is an open-source web application implemented in Python and the Django framework that leverages other commonly-used specialised geodatabase and map server tools. An API provides access to the geodatabase to externally-developed tools. In addition, for an easy installation, the tool is provided as a multi-container Docker application.