Given the huge gap between the prevalence of mental health needs and access to evidence-based interventions, affordable and scalable innovations are at a premium – especially those that intervene in complex systems requiring effective interprofessional, interagency and informal partnering collaborations. The collaborative production method developed in the field of software development known as open-source programming, and the use of products developed by such processes, in particular ‘wikis’ (used as the development space for an approach and training curriculum) may offer benefits. A brief description of open-source processes and an open-source wiki is provided, with Adaptive Mentalization-Based Integrative Treatment (AMBIT, a systemic and organisational application of the mentalizing stance) offered as an example of how these resources created a context for one treatment innovation that has subsequently supported formal trainings and ‘soft influence’ across hundreds of teams worldwide, serving a diverse range of populations (child, adolescent and adult, in a range of mental health, social care and forensic settings) that all share presenting features of multiple complex and intersecting needs, high risk and low response to conventional ‘unimodal’ treatment offers.