To optimize the user interface and experience of your auction app for both web and mobile app development, follow these key steps. Firstly, prioritize a responsive design that adapts seamlessly to various screen sizes, ensuring a consistent experience. Streamline navigation and simplify the bidding process, minimizing steps required to place bids.

Implement intuitive search and filtering options to help users easily find items of interest. Incorporate real-time updates and notifications to enhance engagement. Prioritize fast loading times and smooth interactions, optimizing performance for mobile devices. Regularly gather user feedback and conduct testing to identify areas for improvement, leading to a user-centric and successful auction platform across both web and mobile app development.