Does it split contractions?

No. An apostrophe is kept inside a word, so don't stays one word rather than becoming don and t. Splitting on every non letter is the usual shortcut and it puts a spurious t near the top of any English text. Both the straight and the curly apostrophe are handled, since word processors substitute the curly one silently.

Why are common words included by default?

Because the is being the most common word is sometimes exactly the finding, particularly when you are checking whether writing is repetitive. It is one click to drop them when you want the topic words instead.

Does it work on other languages?

Yes. Words are matched by Unicode letter, so accented and non Latin words are counted as words rather than being split at every character above ASCII. The common word list is English only, so the toggle does nothing useful in another language.

Word Frequency Counter

Which words, and how many times.

Text

Ignore common wordsDrop the, and, of and the rest

Which words, and how many times.

How to use it

Paste the text. Any length up to five million characters.
Decide about common words. Off shows everything. On drops the, and, of and the rest.
Read the list. Commonest first, ties in alphabetical order.

When you would use this

Counting word frequency is a loop and a map, and everything that separates a good result from a useless one happens at the word boundary. The common mistake is splitting on every character that is not a letter. That turns don't into don and t, and since contractions are everywhere in English, t arrives near the top of the list as though it meant something. An apostrophe belongs inside a word, and so does the curly one that word processors substitute without asking. The second is splitting on ASCII only, which breaks café into caf and e and destroys any non Latin text entirely. Matching by Unicode letter instead means accented words and CJK are counted as words. Ties are ordered alphabetically rather than by which word happened to be seen first, so the same text always produces the same list. Common words are included unless you say otherwise, because whether the is your most frequent word is sometimes exactly what you were checking.

Questions

Does it split contractions?: No. An apostrophe is kept inside a word, so don't stays one word rather than becoming don and t. Splitting on every non letter is the usual shortcut and it puts a spurious t near the top of any English text. Both the straight and the curly apostrophe are handled, since word processors substitute the curly one silently.
Why are common words included by default?: Because the is being the most common word is sometimes exactly the finding, particularly when you are checking whether writing is repetitive. It is one click to drop them when you want the topic words instead.
Does it work on other languages?: Yes. Words are matched by Unicode letter, so accented and non Latin words are counted as words rather than being split at every character above ASCII. The common word list is English only, so the toggle does nothing useful in another language.