With growing sustainability and environmental concerns, the maritime shipping route selection process has become more complex, involving simultaneous optimisations across multiple criteria. This paper proposes a user-driven Software-as-a-Service (SaaS) application platform as a decision-support tool for freight forwarders, shippers, and customers, assisting them in optimising route and carrier selection within multimodal transport networks. While traditional approaches, such as multi-criteria decision-making (MCDM) methods have addressed similar decision-making problems in which users can adjust decisions based on their preferences to identify trade-offs, they have largely relied on explicit weight schemes for a fixed set of predefined criteria. In practice, these weights are often challenging to determine, especially in maritime logistics, where each criterion is governed by multiple different stakeholders with conflicting interests. Furthermore, even though customers may prefer different preference elicitation methods, existing application systems in the maritime sector often cannot incorporate diverse user inputs (e.g., weights or aspiration levels). To address these limitations, we propose a Customer-Driven Unified Goal Programming (CD-UGP)-based SaaS application framework that allows decision-makers to express preferences either through aspiration levels or using a weight scheme. The proposed framework is evaluated and validated with multiple real-life scenarios using two case studies focused on optimal container shipping route selection: (i) from Canberra to Colombo, and (ii) from Tokyo to Los Angeles. Results demonstrate that the proposed CD-UGP-based SaaS framework effectively produces more customised and practically relevant routing solutions compared to existing methods.