Sentence case

The real case: text typed all in lowercase

Notes taken in a hurry on a phone, messages copied out of a chat, form fields filled in without looking at the keyboard: when that text has to go into a report, a description or an email, it needs standing back up. Here the capitals return where they belong, at the start of the text and after every full stop, exclamation mark or question mark, across every sentence at once.

How it recognizes a sentence

First the text is put entirely into lowercase, so a stretch accidentally typed in capitals gets evened out too; then a capital goes on the first letter of the text and on the first letter after a full stop, an exclamation mark or a question mark followed by a space or a line break. Accented letters are treated like all the others and punctuation doesn't move.

The three things to check again

Any proper noun loses its capital, because no program can know that «brown» is a surname and not a colour: after the conversion they have to be put back by hand. The same goes for city names, company names and acronyms, which all end up lowercase.

Also, abbreviations open a new sentence: after «etc.» or «Dr.» there's a full stop and a space, so the next word takes a capital even though the sentence carries on. And a line starting after one that didn't end with a full stop does not get a capital: that's right for a text that wraps by itself, less so for a list where every line is its own entry. In that case Capitalize every word or a manual pass works better.

Nearby tools

For titles, where the capital goes on every word, the page is Capitalize every word. To move everything to capitals or to lowercase there is Upper and lowercase. And if besides the capitals your text also has its spaces in disarray, it's worth first running it through Remove extra spaces.