Choose a blank character, pick how many, and copy it.
Different apps accept different invisible characters. The Hangul filler U+3164 and the Braille blank U+2800 count as visible characters to many apps, so they pass validation that rejects an ordinary space. Zero width characters take up no space at all, which makes them useful for watermarking or splitting text invisibly.
The output box looks empty because the characters really are blank. Use the Copy button and paste where you need them. The info line confirms the character code and count.
Some services strip characters they classify as whitespace. Try a different option from the list. The Hangul filler and the Braille blank are the most widely accepted.
They are ordinary Unicode characters. They can however cause confusing bugs in code and form validation, so do not paste them into passwords, usernames used for logins, or source code.
Yes. The Remove Text Formatting and Whitespace Remover tools can strip them, and the Unicode Text Converter shows the code point of every character.