Open-source software frameworks play an important role in advancing problems involving strong coupling between transport, chemistry, and electromagnetic fields. In this work, we present the development and capabilities of an open-source plasma modelling platform, as an extension of the OpenFOAM framework, targeting the simulation of cold atmospheric pressure plasmas (CAPP). The software comprises two standalone plasma solvers, addressing different levels of complexity and accuracy in describing plasma. The first solver resolves detailed plasma chemistry through multi-species transport equations coupled with Poisson's equation for the electric field, enabling the simulation of discharge propagation and reactive species formation. The second solver implements a reduced three-species model, designed for computational efficiency and robustness. Both solvers share reusable libraries, custom boundary conditions, and transport models, following a modular and future-proof design. Another important feature of the platform is its built-in coupling with the BOLSIG+ freeware software for the evaluation of electron transport and reaction rate coefficients. This coupling is achieved through a dedicated Python-based preprocessing and interface toolkit that retrieves cross-section data, executes BOLSIG+ simulations, parses the output, and generates OpenFOAM-compatible input tables, to ensure consistency between kinetic data and solver inputs. This work is directly applied to the simulation of cold atmospheric pressure plasma jets, which are widely used in biomedical applications such as wound healing, cancer treatment, and sterilization. With only a limited number of notable open-source plasma modelling tools available, state-of-the-art multiphysics simulations in this area are still mostly carried out using commercial software (e.g. COMSOL Multiphysics) or in-house codes that are not accessible to the wider research community. The aim of the present work is to provide a flexible and extensible open-source tool capable of addressing the strongly coupled multiphysics nature of atmospheric plasma jets, discuss certification of open-source software, and promote further the open-source plasma community.