Zero Width Stego

Hides a secret message inside ordinary-looking text by encoding it as invisible zero-width Unicode characters. Each bit of the UTF-8-encoded secret becomes either a Zero Width Space (U+200B) for 0 or a Zero Width Non-Joiner (U+200C) for 1, and a Zero Width Joiner (U+200D) separates bytes. The hidden payload is inserted right after the first character of the carrier text.

1. Switch between the Hide and Reveal tabs. 2. In Hide mode, type your secret message and your carrier text (the visible cover message). The default carrier is a pangram; you can edit it. 3. Click Hide; the result looks identical to the carrier but contains the invisible payload. Copy it and paste it anywhere text is preserved. 4. In Reveal mode, paste the text that contains the hidden payload and click Reveal. The decoded secret is shown, or a toast warns you if nothing was found.

The message is UTF-8 encoded into bytes; each byte becomes 8 bits; each 0 bit is U+200B (zero width space) and each 1 bit is U+200C (zero width non-joiner); a U+200D (zero width joiner) is appended after each byte as a separator. The decoder walks every character of the input, accumulates bits for the two zero-width bit characters, and flushes a byte whenever it hits a joiner or after 8 bits accumulate. The carrier text is split at index 1 and the payload is spliced in between, so the first visible character remains unchanged.