Text on a single line

The real case: text that arrives broken up

An address copied from a website, a sentence lifted from a PDF, a title pasted out of an email: they arrive split across several lines, and in a form field, a spreadsheet cell or inside a post that split is a nuisance or isn't even allowed. Here the line breaks disappear all at once and the text goes back to a single line, ready to paste wherever you need it.

What it does exactly

Every line break becomes a space, runs of spaces shrink to one, and the spaces at the start and the end disappear. The text isn't touched in any other way: letters, accents, punctuation and emoji stay identical, and nothing else is added or removed.

Two things to know first

First: the split into paragraphs is lost, and it can't be recovered. If the text was divided into meaningful blocks, afterwards it's one single block: it's worth doing this one piece at a time rather than on a whole document.

Second: if the text comes from a laid-out PDF, words are often broken by a hyphen at the end of a line («conve-\nnience»). Putting everything on one line leaves the hyphen in the middle of the word. That case has a page of its own, which stitches the words back together instead of merely joining the lines: Fix text copied from a PDF.

Nearby tools

If all you need is to drop the extra empty lines while keeping the split into lines, there is Remove empty lines; for double spaces between words, Remove extra spaces. In the opposite direction, to put every entry on its own line with a bullet in front, there is Lines to a list.