Advancing the UN sustainable development goals (UN-SDGs) needs cooperation from both public and private corporations. Involving in open source initiatives is considered risky from an organisational perspective but highly promoted by governments as a way to build digital sovereignty in the European context. Open source initiatives have a greater potential to contribute to digital social innovations (DSI) and advance several UN-SDGs. However, it is not clear to practitioners and IS scholars how might corporations collaboratively pivot and sustain digital social innovations through open source initiatives. To address this practical and theoretical gap, we use a case study method and describe how few corporations associated with the French non-profit association called TOSIT (The Open Source I Trust) collaborate on projects/joint activities to achieve DSIs thereby creating a positive impact to our society. We also delineate a few essential steps for effectively pivoting an open source strategy at an organisational level. This novel guide aims to provide initial clarity to technology managers tasked with undertaking open source initiatives for DSI motives.