Open Farmer Kit is a modular open-source station designed to monitor environmental parameters and biodiversity in small-scale urban farming spaces. Conceived by Valentino Stella and developed with Lorenzo Silvestri, Matteo Mojoli, and Davide Formenti, in collaboration with Polifactory, Open Farmer Kit aims to transfer the benefits of precision agriculture into more social forms of urban farming. This promotes the transition towards collaborative agricultural practices supported by open science. It is a semi-automated system powered by renewable energy sources that operates flexibly, allowing data sampling from different areas of interest. Constructed with easily obtainable electronic components and technologies available in makerspaces, it has a low cost, facilitating adoption and use by end-users. Indeed, Open Farmer Kit offers the opportunity to create local networks for monitoring biodiversity and the health of agricultural ecosystems distributed in cities, facilitating the generation of open data useful to local communities.