What to work through
Work through a spreadsheet as a spoken system design interview. Start by clarifying the scope, sketch a working design and explain the trade-offs behind your choices.
- Scroll and select across a large grid of cells with the mouse and the keyboard
- Edit a cell, in columns that hold text, numbers, dates or true and false
- Write formulas that update when the cells they use change
- Copy and paste a range, and undo and redo
Constraints to discuss
- Scrolling stays smooth across a sheet of a million cells
- A keystroke shows within 200 milliseconds
- A formula result updates within 100 milliseconds of an edit
- Usable with a keyboard and a screen reader
Need a starting point?
Watch for these common gaps as you prepare:
- Storing the sheet as a full two-dimensional array
- Drawing every cell, or redrawing every visible cell on each change
- Skipping the dependency map: a grid with no plan for formulas
- An edge from a formula to every cell of a large range
- Recomputing row and column positions on every render
- Leaning on functions such as the current time that re-run on every change
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.
- Discord: Two May 2026 frontend tips report Google Sheets in the onsite coding round, with the formula logic the part to get right; another tip names a component that works like an Excel cell.
- Clay: A senior software engineer reports a system design round, posted about March or April 2026: a table like a simpler spreadsheet, with rows and columns to add and edit, cells to edit, pasting a range, and typed columns.