The zero-width non-joiner (ZWNJ, U+200C) does the opposite of the zero-width joiner: it prevents two adjacent characters from connecting or forming a ligature. It occupies zero visual space, but it creates an invisible barrier that stops characters from joining.

ZWNJ is essential for correct typography in Persian (Farsi), where it is the most commonly typed invisible character. It has a dedicated key on the standard Persian keyboard layout. In Iran, millions of people type ZWNJ every day without thinking of it as unusual.

Outside of Persian and Arabic typography, ZWNJ has gained popularity as the character used to create blank YouTube video titles and, in some contexts, invisible text on other platforms.

Common Uses

• Persian and Arabic text. In Arabic script, letters automatically connect to adjacent letters. ZWNJ prevents this connection, allowing a writer to place two letters next to each other without them joining. This is essential in Persian, where compound words and certain grammatical forms require a non-joining boundary between connected letter groups.
• Blank YouTube video titles. Copy ZWNJ and paste it as a YouTube video title to create a title that appears empty or invisible to viewers.
• Devanagari script. ZWNJ prevents the formation of conjunct consonants (ligatures) in Hindi, Sanskrit, and other Devanagari-based scripts, forcing the halant (virama) to be visible instead.
• Preventing ligatures in professional typography. In some design contexts, you may want to display characters separately rather than as a ligature (e.g., showing "fi" as two separate letters instead of the "fi" ligature).

How to Type

ZWNJ in Persian Typography

To understand why ZWNJ matters so much in Persian, you need to understand how Arabic script works. Letters in Arabic script have up to four forms depending on their position: isolated, initial, medial, and final. Letters automatically connect to their neighbors.

Persian uses the same script but has different rules about when compound words should show connections between their parts. Consider a Persian compound word made of two smaller words. In Arabic, all the letters would connect across the word boundary. In Persian, the writer needs to show where one word ends and the next begins, without inserting a visible space.

ZWNJ solves this perfectly. It breaks the letter connection at exactly the right point without adding any visible gap. The letters appear close together (as they should in a compound word) but do not connect across the boundary.

This is so common in Persian that ZWNJ has a dedicated key on Persian keyboards. Persian writers use it dozens or hundreds of times per day. It is estimated that ZWNJ appears in roughly 1-2% of all characters in typical Persian text.

Example

In Persian, the word for "library" (ketab-khaneh) is a compound of "book" + "house." Without ZWNJ, the letters connect across the boundary, making it look like a single morphological unit. With ZWNJ, the two parts remain visually distinct while staying close together.

YouTube Blank Title Trick

To create a blank YouTube video title:

1. Copy the ZWNJ character from the copy button at the top of this page.
2. Go to YouTube Studio and open the video you want to edit.
3. Clear the existing title and paste the ZWNJ character.
4. Save. The title will appear blank to viewers.

Note that YouTube may update its validation at any time. If ZWNJ stops working, try Zero-Width Space (U+200B) or Hangul Filler (U+3164) as alternatives.

Why ZWNJ Works for YouTube

YouTube requires a non-empty title to publish a video. ZWNJ is classified as a Format character (Cf), which YouTube's validation treats as valid content. Because it has zero width and no visible glyph, the title appears blank. This is different from using a regular space, which YouTube would likely strip or reject.

Technical Details

• Unicode category: Cf (Format). It is a formatting character, not a space or letter.
• Width: Zero. It produces no visible glyph.
• Joining behavior: Forces the characters on either side to use their non-joining (isolated or final/initial) forms instead of their connected forms.
• Line breaking: Does NOT create a line-break opportunity. Unlike zero-width space, ZWNJ keeps the text together.
• Bidirectional behavior: Inherits the direction of the surrounding text.

In JavaScript:

// Detect ZWNJtext.includes('\u200C')
// Remove all ZWNJ characterstext.replace(/\u200C/g, '')
// ZWNJ is common in Persian text - you may not want to strip it// from user input without understanding the context

Security Considerations

• Internationalized domain name confusion. ZWNJ is allowed in some internationalized domain names (IDN). Two domains that look identical might differ by a hidden ZWNJ, potentially enabling phishing.
• Email address confusion. Internationalized email addresses can contain ZWNJ, creating addresses that look the same but are technically different.
• Text comparison failures. Strings containing ZWNJ will not match strings without it, even if they look identical on screen.

ZWNJ vs Similar Characters

ZWNJ and ZWJ are direct opposites. ZWNJ says "do not connect these characters." ZWJ says "connect these characters." See our Zero-Width Joiner page for details on how ZWJ creates emoji and forces letter connections in Arabic script.