[gary_chambers]

Both rrweb and OpenReplay are very solid projects. I've spent the last year or so building a session recording tool, and I've scrutinised their code quite heavily. Conceptually, session recording is quite simple, but there are so many edge cases, security models (CSP, feature policies) and performances issues to overcome.

Performance is probably the area I've spent the most time thinking about: if you want to measure performance regressions in a page, instrumenting it with a session recorder is definitely a way to skew the results (for example, checking scroll position of elements during snapshotting will trigger a reflow).