Hi everyone,
I’m a CS student and chess player who built a tool I think some of you might find useful for tournament preparation.
Chess Stalker (chessstalker.com) analyzes your opponent’s games and shows you:

     ∙      Their opening repertoire as White and Black (with specific lines and transpositions)
     ∙      Weaknesses and patterns (where they blunder, time trouble tendencies, etc.)
     ∙      Psychological profile (how they handle losing positions, drawish endgames, etc.)
     ∙      Suggested preparation lines based on their gaps

It works with Lichess, Chess.com, and FIDE/OTB games (1.7M+ players indexed from FIDE database, 11M+ OTB games).
The OTB part might be especially interesting for this community - you can look up classical players and see their repertoire evolution over years of tournament play.
Completely free, no account needed. Just search a username or FIDE name.

Would love feedback from serious players  - what would make this more useful for your preparation?
Cheers,