Sustainable Funding for Open-Source Critical Infrastructure: Balancing Free Access and Revenue Generation

Introduction: The Open-Source Sustainability Paradox Open-source software underpins the digital economy, from web servers to critical infrastructure. However, its foundational principle—unrestricted access to source code—creates a sustainability paradox: how can projects secure financial viability while preserving openness? This tension is most acute in critical infrastructure, where underfunding compromises security, and proprietary shifts erode trust. The case of ZITADEL , an identity platform, exemplifies this challenge and introduces a solution through the AGPL 3.0 license and a "Risk Transfer" monetization model. Under the Apache 2.0 license , ZITADEL encountered a systemic open-source issue: corporate users exploited the software without contributing resources . This free-rider problem threatened sustainability, as critical infrastructure demands costly security audits and penetration testing. Transitioning to AGPL 3.0 introduced a reciprocity mechanism: commercial users must eit