Zero‑width characters are special Unicode characters that have no visible glyph — they take up no width when rendered. The most common ones are Zero Width Space (U+200B), Zero Width Non‑Joiner (U+200C), and Zero Width Joiner (U+200D). Although invisible to the eye, they are real characters that can be copied, pasted, and detected by software. Our tool uses them to encode binary data — turning your secret message into a sequence of invisible characters.

We convert each character of your message into its 16‑bit binary Unicode code point. Then, we replace every 0 with a Zero Width Space (U+200B) and every 1 with a Zero Width Non‑Joiner (U+200C). Characters are separated by Zero Width Joiners (U+200D), and special marker sequences (three consecutive ZWJs) wrap the entire message. This encoded sequence can then be appended to any visible "carrier" text — making the hidden message virtually undetectable.

Most modern platforms preserve zero‑width characters, including Twitter (X), Facebook, Instagram, WhatsApp, Telegram, Discord, Slack, iMessage, Gmail, and standard text editors. However, some platforms may filter or normalize certain Unicode characters. For best results, test on your target platform first. Note that platforms with aggressive text sanitization (like some banking apps or secure messaging systems) might strip them.

No, this is not encryption. It is steganography — the art of hiding information in plain sight. Anyone who knows about zero‑width characters and has access to a decoder (like this tool) can extract the hidden message. There is no password or key protection. For truly secure communication, combine this with actual encryption (e.g., AES or PGP) before encoding. Think of it as "hiding," not "locking."

Yes. While invisible to the human eye, zero‑width characters can be detected by tools that inspect Unicode code points, count string lengths, or highlight invisible characters. Some platforms and browser extensions can reveal them. Our decoder also detects and reports the count of zero‑width characters in any pasted text — even if no complete hidden message is found.

Legitimate uses include: digital watermarking (embedding author info in text), creative puzzles and ARGs (alternate reality games), hidden signatures in documents, covert communication in restrictive environments, tamper detection (if the invisible text is removed, you know the content was altered), and educational purposes to teach about Unicode and steganography. Please use this tool responsibly and ethically.

This can happen if: (1) the zero‑width characters were altered or partially stripped by the platform, (2) the text contains extra invisible characters that interfere with the marker detection, (3) you're trying to decode text that was not encoded by this tool, or (4) the carrier text itself accidentally contains zero‑width lookalike sequences. Always test the round‑trip (encode → decode) to verify integrity before sharing.

Each character in your secret message is encoded as 16 zero‑width bits (using ZWSP for 0 and ZWNJ for 1), plus one ZWJ separator between characters. So a 10‑character message produces roughly 170 invisible characters (10 × 16 bits + 9 separators), plus the 6‑character marker wrapper. This means longer messages create more invisible data — but since it's zero‑width, it still occupies zero visual space.