Session Replay: What It Is, How It Works, and When You Need It

Session replay tools record user interactions by capturing a full DOM snapshot and subsequent mutations using rrweb, producing lightweight reconstructed replays rather than video files. While powerful for understanding user behavior, these tools pose significant privacy risks by potentially capturing sensitive data like passwords and credit card numbers unless explicit masking and element exclusion are configured. Most major tools now offer input masking, element exclusion, and text masking as privacy controls, but the fundamental challenge of serializing the entire rendered DOM remains.