Rotterdam doesn't get the same coffee-city reputation as Amsterdam, which is exactly why it's worth a slower look. The scene here is smaller, a little less polished, and easier to actually get a seat.
Start in the morning somewhere near the market hall, when the roasters are still working the bar themselves. Order a filter, not a flat white, if you want to actually taste what's in the hopper that week.
Mid-afternoon is for the spots that double as workspaces — long tables, good light, coffee that holds up over a couple of hours rather than being built for a single quick shot.
Evenings are quieter for coffee, which is the point: a smaller pour, a slower conversation, no rush to give up the table.
None of this needs a reservation or a plan. Rotterdam rewards wandering more than most cities we've spent a weekend in.