How do I know if text contains zero-width characters?

You can't see them — that's the point. Paste the text here and the decoder reports exactly which invisible code points are present and where.

Why would text be watermarked this way?

To identify the source of a leak. Give each recipient a copy with a slightly different invisible pattern, and a leaked document identifies who leaked it — without changing a single visible character.

How do I remove zero-width characters?

Strip the code points U+200B–U+200D and U+FEFF, or round-trip the text through a strictly ASCII field. Note that removal also destroys any legitimate typographic use of the joiners.

Zero-Width Steganography Decoder

Extract hidden messages encoded in invisible zero-width Unicode characters.

live · client-sideClassical & Obfuscated Ciphersfree · no sign-up

RAW INPUT

DECODED

Output appears here as you type — decoded on your device.

Input is processed on your device. Nothing you paste is sent anywhere.

What is the Zero-Width Steganography Decoder?

A zero-width decoder finds invisible Unicode characters — zero-width space, non-joiner, joiner and word joiner — inside ordinary text and decodes the binary message they encode.

Several Unicode code points render as nothing at all: U+200B zero-width space, U+200C non-joiner, U+200D joiner and U+FEFF word joiner. They exist for legitimate typographic reasons in scripts like Arabic and Devanagari, but because they are invisible in most contexts they make an excellent covert channel — assign one character to 0 and another to 1, and any text can carry a hidden binary payload.

The technique is used both benignly and otherwise. Document watermarking embeds a per-recipient fingerprint so a leaked file can be traced back to whoever received it. The same trick can smuggle data past filters, hide prompt-injection instructions inside text destined for an AI system, or tag copy-pasted content invisibly.

Paste any suspicious text here and the decoder reports which zero-width characters are present, where they appear, and what message they spell out.

Zero-Width Steganography Decoder at a glance

Characters: U+200B, U+200C, U+200D, U+FEFF and friends
Visibility: Render as nothing — invisible in normal text
Encoding: One character per bit, or per symbol
Uses: Watermarking, fingerprinting, covert channels

How to use the Zero-Width Steganography Decoder

1Paste the suspect text, keeping formatting intact — copying via a plain-text field can strip the characters.
2The decoder reports any zero-width characters found and their positions.
3Read the decoded hidden message, if the characters encode one.

When you would reach for it

Checking a leaked document for an invisible per-recipient watermark.
Detecting hidden instructions smuggled into text fed to an AI system.
Solving a steganography challenge in a CTF.

Zero-Width Steganography Decoder — frequently asked questions

Last reviewed 25 July 2026 · questions or corrections: contact@decoder.tools