Combine & Merge Lists Online
Merge two separate lists together instantly. Append them end to end, alternate them line by line, or join them side by side with a custom separator. Nothing is uploaded.
Related text manipulation tools
The three merge methods
Append puts List B directly below List A. Nothing is interleaved or rearranged, it is the simplest possible merge: everything from List A first, then everything from List B underneath. Use this when the two lists are extensions of the same set, two exports that belong in one combined file.
Alternate works like a zipper. It takes the first line of List A, then the first line of List B, then the second line of A, and so on down both lists. This is the right mode for pairing items that need to stay adjacent but distinct, like matching questions with answers, or building a dual-language flashcard deck where each term is followed immediately by its translation.
Side-by-Side Join glues corresponding lines together on the same row rather than stacking them. Line 1 from List A joins with Line 1 from List B, separated by whatever character you set in the Separator field. A comma produces CSV-ready output. A pipe or dash works for anything meant to stay human-readable.
What happens with unequal list lengths
If List A has 40 lines and List B has 25, the tool does not throw an error or drop anything. In Alternate and Side-by-Side Join modes, once the shorter list runs out, the remaining lines from the longer list continue printing on their own for the rest of the output. You do not need to pad the shorter list with blank lines to make the counts match first.
Where this gets used
Building CSV data from two spreadsheet columns
Two columns copied separately out of a spreadsheet, names in one paste and emails in another, need to become a single comma-separated column before most import tools will accept them. Paste each column into List A and List B, select Side-by-Side Join, set the separator to a comma, and the output is ready to paste directly into a new spreadsheet column or CSV file.
Generating keyword and ad copy combinations
Paid search campaigns often need every combination of a modifier list against a product or location list, “best” plus every city name, or a headline template plus every product variant. Side-by-Side Join with a space separator turns two short lists into a full set of combined phrases in one pass, which is considerably faster than typing out each combination by hand or building a spreadsheet formula for it.
Pairing questions with answers or terms with translations
Alternate mode is built for exactly this. A list of vocabulary terms in List A and their translations in List B, run through Alternate, produces a single list where each term is immediately followed by its match, ready to paste into a flashcard app or study document without manual reordering.
Stacking two exports into one working file
Combining this month’s export with last month’s, or merging two team members’ separately compiled lists, is a straightforward Append job. Once the combined list exists, the remove duplicate lines tool catches any entries that appeared in both original lists.