The entries appear in no particular order.

• The one and only Richard Stanley: homepage
• Igor Pak: homepage, blog and his famous collection “What is Combinatorics?“
• Doron Zeilberger: homepage and his famous Opinions
• Xavier Viennot: homepage
• Federico Ardila: his amazing youtube channel
• Gil Kalai: homepage and blog
• Peter Cameron: homepage and blog
• Terence Tao: homepage and his famous amazing blog
• Timothy Gowers: homepage and blog
• Matt Baker: homepage and blog
• Yufei Zhao: homepage and blog

• Two lists of conferences in combinatorics
• OEIS (the famous encyclopedia of sequences)
• FindStat (encyclopedia of combinatorial statistics)
• SageMath (favourite for many in algebraic combinatorics)
• Manim (amizingly beautiful math animations)
• math arXiv (the databes of math preprints)
• MathSciNet (the database of published math articles)

• List of (old) videos of Combinatorics for general audience and why you should watch them (by Igor Pak)
• Numberphile
• An amazing talk from another era
• A few amazing lectures by the inimitable John Horton Conway
• Video interviews of John Horton Conway, Ronald Graham, Laszlo Lovasz, Endre Szemerédi and more
• A lot of interesting interviews to top combinatorialists: every volume contains some. Also check out historical articles and surveys

• Math olympiads
• Giornalino degli open days di matematica
• Orientamento per studenti di scuola superiore