Multi-Selection Dropdowns in Google Sheets

Google Sheets drop-downs are single-pick by default, which is annoying when the real world wants multi-pick (skills, tags, colors, statuses). One practical workaround is an onEdit(e) Apps Script that watches a specific drop-down cell, then appends each new selection to the existing cell value as a comma-separated list. The smarter version splits the existing string into an array, trims whitespace, checks whether the new pick is already present, and only adds it if it is genuinely new, so you avoid duplicate entries and the classic XS vs S substring bug.

If you want it beyond one cell, you can widen the trigger logic, target a whole column, or multiple columns by adjusting the row/column checks in the if statement.

There's a guide on spreadsheet point: https://spreadsheetpoint.com/multiple-selection-drop-down-google-sheets/