When attending in-person professional events, we often forget who we met or miss chances to connect with others. For example, we may forget to exchange business cards or add new contacts on LinkedIn. Additionally, we may be unaware of interesting people who were nearby or also attended the event. Our research explores how to capture these missed networking opportunities using opportunistic networking, inspired by the concept of the “Familiar Stranger” by Paulos and Goodman [18]. This refers to people we repeatedly encounter at events, making them feel familiar, yet we never formally meet them. We propose a platform that records social proximity and interactions at events using Bluetooth and event activity data from mobile phones. To support this, we conducted a survey on how people network at events and explored early methods for detecting and recording proximity interactions. This data can be used to recommend potential connections based on attendees’ encounters during the event.