Hidden Text

What it's for

Hide a secret inside ordinary text using characters that don’t show, and find characters like these in text you receive. Invisible characters are also used to watermark text, to track where it was copied, and to slip hidden instructions to AI tools.

• When you’re setting a puzzle or sending a message that should look like something else.
• When you’re checking text you’ve been sent, or copied from a web page, for anything hidden in it.
• When you need a clean copy of text without zero-width spaces, direction marks or other invisible characters.

How to use it

Under Hide, type the cover text and the secret; the text with the secret in it appears as you type, ready to copy. Choose how it’s hidden (remembered):

• Zero-width characters carry any text, as a run of zero-width spaces and non-joiners after the first character.
• Unicode tag characters carry only plain ASCII, and are used in “ASCII smuggling” against AI tools.
• Variation selectors carry any text in the fewest characters; they’re placed after the first emoji, if there is one.

Under Find and reveal, paste text: it counts every invisible character, decodes any message hidden in the three ways above, and gives the text with all of them removed. The emoji presentation selector (U+FE0F), part of normal emoji, is kept.

Example

Type this as the cover text:

See you at the usual place

and Gate code 4471 as the secret. The result looks the same as the cover text. Copy it, paste it into Text to check, and it shows Zero-width binary: Gate code 4471.

Good to know

Some apps and websites strip invisible characters, which loses the secret, and some show them as boxes. Hiding isn’t encryption: anyone with a tool like this can read the message. The detector finds zero-width and formatting characters, direction controls, tag characters and variation selectors, but not look-alike letters from other alphabets; use the Character Inspector for those.