The Mumbai Transport Stack is being developed as a digital public infrastructure built on open standard data exchange protocols and the Mobility as a Service (MaaS) framework, designed to make different modes of transport interoperable. The Mumbai Metropolitan Region Development Authority (MMRDA) said the platform will enable secure data exchange between Metro, bus, suburban rail and other systems. The architecture is founded on five core principles: open source, interoperability, privacy by design, trusted and secure systems and scalable design. The stack is intended to act as a secure data backbone allowing seamless communication among transport operators, government agencies and mobility service providers. Its open application programming interface architecture will permit private innovators to develop new mobility solutions spanning ticketing, trip planning and analytics. This approach aims to foster a broader ecosystem of services while maintaining standardised data flows. Governance mechanisms and common standards are expected to guide data sharing and ensure interoperability across stakeholders. For commuters, the initiative is expected to enable end-to-end ticket booking, real-time tracking of trains, buses and Metro services, seamless multimodal trip planning and access to real-time parking information. The integration of these services is intended to reduce friction when switching between modes and to shorten journey times for daily travellers. Operators anticipate that standardised interfaces will also make it simpler to scale services across the Mumbai Metropolitan Region. Beyond immediate commuter benefits, the integration of real-time mobility data should assist in smarter urban planning and infrastructure development. The MMRDA underlined that privacy by design and trusted security will be central as data highways are established. If implemented at scale, the Mumbai Transport Stack could form the foundation for a unified, intelligent transport network across the region. Stakeholders will need to coordinate planning and operations to realise full benefits over time.