To enhance the efficiency of steel structure design, engineers utilise a wide range of tools and software. Despite their utility, these tools are often hampered by limitations in flexibility, reliability, and interoperability. As a result, the routine design process remains highly iterative and error prone. The emergence of Application Programming Interfaces (APIs) offers a new pathway to shift towards more streamlined workflows, enabling seamless system integration, application customisation, automation of repetitive tasks, and secure data exchange. This paper develops a novel web-based API for the parametric design of Australian steel structures. This proposed API integrates with a central steel design database to provide endpoints for access and filtering of steel structure design data. The API enables streamlined integration in user structural design workflows, and for downstream extensible integration with more complex structural design software. Through this approach, the paper seeks to contribute to improved digital workflow efficiency and automation for steel structure design processes.