TkN is a C++/ROOT library designed for nuclear-structure and gamma-ray spectroscopy analysis, providing a unified toolbox to handle experimental observables and interface with nuclear databases (level schemes, γ transitions, branching ratios, etc.). It is used as a backend by analysis applications such as Cubix, enabling direct access to evaluated nuclear data within standard spectroscopy workflows. The source code is available on Gitlab: https://gitlab.in2p3.fr/ip2igamma/tkn/tkn The TkN project is governed by the CeCILL-B license under French law and abiding by the rules of distribution of free software. You can use, modify and/or redistribute the software under the terms of the CeCILL-B license as circulated by CEA, CNRS and INRIA at the following link www.cecill.info.