A reproducible word convention
L’école porte-monnaie don't 3.14 Hello—world contains five whitespace-separated words. An apostrophe, internal hyphen or decimal mark does not split a chunk. A punctuation-only chunk does not count. The alternative browser segmentation can split these differently: record which method you selected instead of assuming a word processor or portal uses the same one.
One visible character can occupy several units
The sequence A😀é followed by a line break has four visible characters, five code points, six UTF-16 units and nine UTF-8 bytes. The accent is a separate combining code point. No normalization is applied to the original draft. A downloaded source file can include a byte-order mark or different line endings, so this is a measurement of the editor contents rather than a file-size validator.
Counting basis
Default words are whitespace-separated chunks containing a letter or number. Internal apostrophes, hyphens and decimals stay together. The browser alternative can differ. Space switches affect visible-character counts, not original bytes or words. Check whether your brief specifies words, visible characters or bytes, and whether titles, references and line breaks count. This counter does not decide those rules. A selected excerpt or explicit included sections avoids accidentally counting the wrong material.