I didn't see anyone mention the McMaster-Carr website [1]. It may not be the "densest" out there, but it's clean, functional, and nicely presents a lot of information at once. [1] https://www.mcmaster.com/
Even though it’s never failed to connect me with precisely the part I’m seeking, to this day their interface spooks me a little: where are they hiding the endless walls of text and part numbers, the kaleidoscopic wall of bins?!