Zero-width text encoder & decoder

Hide a message in ordinary text, or inspect text for invisible Unicode characters.

Runs locally in your browser. Nothing is uploaded.

Try an example:
This stays readable and unchanged. The hidden message is woven into it invisibly.
0 chars
Keep it short — longer messages create more zero-width characters, increasing detectability
Advanced options Standard mode
Compatibility
Best for most uses. Produces a shorter, less noticeable payload.
The receiver will need the exact same passphrase. New messages verify that the passphrase is correct, but this remains obfuscation rather than encryption.

This hides a message; it does not encrypt it. Don’t use it for sensitive information.

Your encoded text
Encoded message will appear here.

Paste text below and StegZero will inspect it automatically.
If it contains a hidden message, it will appear right away.

Hidden characters are invisible, so suspicious text may look completely normal.
Unicode inspection options content type, file, advanced checks

Files are inspected only in this browser, are not uploaded, and are not saved in local storage. Maximum 1 MiB and 500,000 Unicode code points.

Current passphrase-protected messages verify the passphrase before showing a result. Older messages may not support verification.
Reveal result
Paste text above to begin.

Need a standalone tool? Open the Invisible Unicode Character Detector.

.txt & .md .html & .xml .csv .json 100% client-side

Drop a text file here or click to browse

.txt · .md · .html · .xml · .csv · .json

This ID will be invisibly embedded throughout the file. Keep it unique per recipient or distribution copy.

Drop the file to inspect or click to browse

.txt · .md · .html · .xml · .csv · .json

How Zero-Width Steganography Works

What is zero-width steganography?

  • A technique for hiding secret messages inside ordinary visible text
  • Uses invisible Unicode characters — zero-width spaces, joiners, and separators
  • Unlike encryption, it hides the existence of a message, not just its contents
  • The cover text looks and reads completely normally to any human reader

Standard vs Compatibility mode

  • Standard (default): uses eight zero-width characters — three bits per symbol for a shorter payload
  • Compatibility: uses only ZWSP (U+200B) and ZWNJ (U+200C) — one bit per symbol
  • Compatibility payloads use about three times as many carrier characters, but the smaller alphabet may be preserved by more platforms
  • The local verification button checks StegZero itself. To test another platform, send the encoded text through it and paste the received result into Reveal.

Platform compatibility

  • Twitter/X and Facebook strip zero-width characters — messages will be lost in both modes
  • WhatsApp may strip some rarer characters — Compatibility mode may work better, but verify it before relying on it
  • Email, Telegram, Discord, and plain text files generally preserve all ZW chars
  • Always copy a test message through the target platform and paste the received text into Reveal before relying on it

Good use cases

  • Hiding watermarks in shared documents to track leaks
  • Easter eggs in web pages, GitHub READMEs, or blog posts
  • Puzzles and alternate reality games (ARGs)
  • Learning about Unicode, text encoding, and digital steganography

Passphrase obfuscation layer

  • The optional passphrase applies XOR obfuscation to the message bytes before they are encoded as zero-width characters
  • New passphrase-protected messages verify the passphrase before displaying decoded text; older StegZero messages may not support that verification
  • XOR obfuscation is not cryptographic encryption and should not be treated as such — it adds obscurity, not security
  • For genuinely sensitive content, encrypt with GPG or AES-256 first, then encode the ciphertext here with a passphrase on top

Zero-Width Steganography — Frequently Asked Questions

Is zero-width steganography secure?

  • No — it's obfuscation, not encryption. Pasting into any decoder reveals the message.
  • For real security: encrypt with GPG or AES first, then hide the ciphertext here.
  • The optional passphrase adds XOR obfuscation but is not cryptographically strong.

Which Unicode characters are used?

  • Standard: ZWSP (U+200B), ZWNJ (U+200C), ZWJ (U+200D), Word Joiner (U+2060), Invisible Times (U+2062), Invisible Separator (U+2063), Invisible Plus (U+2064), BOM/ZWNBS (U+FEFF)
  • Compatibility: only ZWSP (U+200B = bit 0) and ZWNJ (U+200C = bit 1) — a smaller, more widely preserved pair

How do I decode a steganography message?

  • Paste the text into the Reveal tab above. StegZero automatically inspects it and extracts hidden messages in Standard, Compatibility, and legacy formats.

Is my data sent anywhere?

  • No. Everything runs in your browser via JavaScript.
  • No text is ever sent to a server — not even anonymised telemetry.
  • The full source code is open on GitHub for independent verification.

How does file watermarking work?

  • The watermark ID is encoded as zero-width characters using the Standard engine
  • Characters are distributed across safe text positions — avoiding JSON values, CSV numbers, etc.
  • The original file content is completely unchanged — only invisible characters are added
  • Upload a suspected leaked copy to the Verify pane to instantly extract the watermark ID

Can StegZero decode Steghide files?

  • No — Steghide is an image and audio steganography tool that hides data inside JPEG/BMP/WAV files. StegZero handles text steganography using invisible Unicode characters.
  • If you have a Steghide-encoded image, you need the steghide command-line tool or a dedicated image steg decoder — not StegZero.
  • If you have text that looks normal but may contain a hidden message, you're in the right place — paste it into the Reveal tab above.
  • Other tools StegZero doesn't cover: Snow (whitespace steganography), OpenStego, and MP3Stego.

How to decode a hidden text message

  • Step 1: Copy the text you suspect contains a hidden message — it will look completely normal
  • Step 2: Open the Reveal tab above and paste the text into the input field
  • Step 3: StegZero automatically inspects the text and reveals Standard, Compatibility, and legacy messages
  • Step 4: If the message was encoded with a passphrase, toggle the passphrase option and enter it before decoding
  • Open Unicode inspection details to see which invisible characters and message format were found