Complex sentence: Maciej Cegłowski is a Polish-American web developer, entrepreneur, speaker, social critic, based in San Francisco, California, who is the owner of the bookmarking service Pinboard, which he calls a social bookmarking site for introverts.
Split into simpler sentences: Maciej Cegłowski is a Polish-American web developer, entrepreneur, speaker, social critic, based in San Francisco, California. He is the owner of the bookmarking service Pinboard, which he calls a social bookmarking site for introverts.