What to work through
Work through a live map of points as a spoken system design interview. Start by clarifying the scope, sketch a working design and explain the trade-offs behind your choices.
- Show every sign-up as a point on a world map
- Add new sign-ups to the map as they happen
- Zoom from the whole world down to one street and pan around
- Click a point or a group of points to see what is there
Constraints to discuss
- Panning and zooming stay at 60 frames a second
- The page never loads the whole data set, only what the view needs
- A burst of sign-ups never freezes the map
- A pan, a zoom or a click answers within 200 milliseconds
Need a starting point?
Watch for these common gaps as you prepare:
- One page element for each point
- Loading the whole data set into the browser
- Redrawing the map for every new sign-up
- Fetching on every movement without cancelling the old requests
- Doing the grouping on the main thread
Why this question is in the collection
These sources connect the problem to company interview reports or preparation guides. They do not guarantee what a company will ask you.
- LinkedIn: A frontend candidate reports a frequent virtual onsite question, posted January 2024: show where newly registered users are on a map, with follow-ups on how often to update, a burst of sign-ups, the data the server sends, and polling against an open connection.
- LinkedIn: Another frontend candidate, posted November 2023: the UI system design round was a map that shows new user registrations by place.
- Meta: A frontend candidate, posted July 2024: the system design question was a dashboard of newly registered users that includes a map.