How to interleave two lists line by line
When you copy two columns out of a spreadsheet, or keep a vocabulary list and its translations in separate files, you often need to weave them together one line at a time. This tool pairs the first line of list A with the first line of list B, then the second with the second, and so on. It is handy for building flashcards, pairing names with email addresses, or lining up a subtitle script with its translation.
The separator decides how each pair is joined. Choosing a line break produces A1, B1, A2, B2 on their own lines, while tab or comma puts both values side by side on one line so the output can be pasted straight back into a spreadsheet. If you need a different symbol, type it into the custom separator box.
When the two lists have different line counts, you can either append the leftover lines from the longer list or stop at the shorter one and drop them. Either way the summary above the output shows the real line count of each list, how many pairs were created, and exactly what happened to the leftovers, so nothing disappears silently. Trailing blank lines at the end of each box are ignored. Each list accepts up to 100,000 characters.
Frequently asked questions
By default the tool interleaves as many pairs as it can and then appends the leftover lines from the longer list at the end. Switch the option to stop at the shorter list if you would rather discard them, and the summary tells you which list had leftovers and how many.
Yes by default, so the pairing order stays aligned with your original files. Switch the blank line option to remove them, and the summary reports how many blank lines were dropped before merging.