Hidden Unicode Zero-Width Space Detector

Find invisible tracking characters often hidden in copied web text. Detect, visualize, and strip non-printing Unicode characters in real time. 100% client-side, nothing ever leaves your browser.

🔍 Detection Workspace
Panel 1 - Paste Text to Inspect
0 characters Awaiting input
Panel 2 - Anomaly Overlay Visualizer
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Awaiting Input
Panel 3 - Telemetry and Sanitizer
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Total Hidden Characters Found
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Distinct Categories Detected
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Visible Characters (Clean)
Character Category Breakdown
No hidden characters detected. Paste text above to begin scanning.
Key Terms Explained
Zero-Width Space (ZWSP)
A Unicode character (U+200B) that has zero visual width and is completely invisible on screen. Used as a potential line-break hint in typography, it is also widely inserted into text to embed hidden watermarks that survive copy-pasting.
Unicode
An international standard that assigns a unique numeric code point to every character in every writing system, plus thousands of control, formatting, and symbolic characters, including invisible ones used for text manipulation and tracking.
Non-Printing Character
Any character that occupies no visible glyph on screen or in print. Non-printing characters include control codes, formatting marks, and zero-width characters that affect layout or encoding without being visible to the reader.
Digital Watermarking
The practice of embedding a hidden, often unique identifier into content to enable later verification of its origin or to detect unauthorized distribution. Text watermarking uses invisible Unicode characters to encode user-specific bit patterns inside readable prose.
Text Obfuscation
The deliberate insertion of invisible or misleading characters into text to confuse search engines, content filters, plagiarism detectors, or human readers. Zero-width characters are one of the most common and difficult-to-detect obfuscation techniques.
Sanitization
The process of removing or neutralizing unwanted, unexpected, or potentially harmful content from a string. Text sanitization for Unicode means stripping all non-printing and invisible characters before the string is stored in a database or used in source code.
Hex Code
A hexadecimal (base-16) representation of a character's Unicode code point. For example, the zero-width space is written as U+200B, where 200B is the hex value. Hex codes are the standard notation used to identify and reference specific Unicode characters in documentation and code.

The Complete Guide to Hidden Unicode Characters and Text Sanitization

Not everything in a block of text is visible to the human eye. Between the letters and spaces you can read, a string can contain dozens of invisible Unicode characters that affect how the text behaves in code, how it is watermarked for tracking, and whether it will cause silent failures in applications. This tool exposes every one of them instantly.

How to Use This Tool

Paste any text into the Detection Input panel on the left. The scanner reads every character in real time and immediately updates the Anomaly Overlay on the right. If a hidden character is found, it appears at its exact position as a labeled amber badge (for example, [ZWSP] or [ZWJ]) so you can see precisely where it was hiding within the surrounding visible text. Hover over any badge to see the full Unicode name and code point in a tooltip.

The Telemetry panel below shows the total count, the number of distinct character categories detected, and a per-category breakdown with exact counts. To remove all detected characters at once, click Strip All Hidden Characters. The input panel updates with the cleaned text, which you can then copy to your clipboard with the Copy Clean Text button.

Which Unicode Characters Are Detected

This tool scans for the full spectrum of commonly misused invisible and non-printing Unicode characters:

Code Point Name Badge Label Common Use or Misuse
U+200B Zero-Width Space [ZWSP] Line-break hints, text watermarking, tracking
U+200C Zero-Width Non-Joiner [ZWNJ] Arabic/Persian typography, binary watermarking
U+200D Zero-Width Joiner [ZWJ] Emoji sequences, watermarking, obfuscation
U+200E Left-to-Right Mark [LRM] Bidirectional text control, steganographic use
U+200F Right-to-Left Mark [RLM] Bidirectional text control, steganographic use
U+FEFF Byte-Order Mark / ZWNBS [BOM] File encoding marker, often silently copied from documents
U+2060 Word Joiner [WJ] Prevents line breaks; used to hide text in content scrapers
U+2061 Invisible Function Application [FUNC] Mathematical markup, invisible in plain-text contexts
U+2062 Invisible Times [ITIMES] Mathematical markup, invisible in plain-text contexts
U+2063 Invisible Separator [ISEP] Mathematical markup, invisible in plain-text contexts
U+2064 Invisible Plus [IPLUS] Mathematical markup, invisible in plain-text contexts
U+180E Mongolian Vowel Separator [MVS] Mongolian script; historically misused as a zero-width alternative

How Text Watermarking Uses Invisible Characters

When a publisher or platform wants to identify which specific user leaked a confidential document, they generate a unique bit string for each user account before serving them the page. The bits are encoded by inserting specific zero-width characters between the words of the document. A Zero-Width Space might represent a binary 1, while a Zero-Width Non-Joiner represents a binary 0. Every user sees what appears to be identical text, but each copy carries a unique invisible fingerprint.

This technique survives copy-pasting because clipboard operations copy all Unicode code points, including invisible ones. The only defenses are to strip all invisible characters before sharing any text, or to retype the content from scratch. This tool handles the stripping in a single click.

Why Hidden Characters Break Code and Databases

A very common source of frustrating, hard-to-reproduce bugs is copying a value from a webpage, PDF, or documentation site into source code, a config file, or a form field. An API key that looks correct will fail authentication if it contains a single zero-width space that the developer cannot see in the editor. A database query will silently return zero results because the string comparison fails. A JSON property key copied from documentation will not match the expected field name, causing the entire object to be ignored at runtime.

Pasting any copied value through this detector before using it in code eliminates this entire class of invisible-character bug. Developers who work frequently with copied API keys, environment variable values, and configuration strings will find this tool especially useful as a mandatory sanitation step.

FAQ: Invisible Unicode Characters and Zero-Width Spaces

A zero-width space (U+200B) is a Unicode character that occupies no visible width and renders as nothing on screen. It is legitimately used in some languages and typesetting systems to indicate potential line-break points where a space character would look wrong. However, it is also placed inside text by some websites and content management systems to act as a hidden watermark or tracking token, allowing the original source of a leaked document or copied content to be traced back to a specific user or session.
Publishers and platforms can encode a unique binary fingerprint by placing different combinations of zero-width characters at specific positions in a document. For example, a Zero-Width Space might represent a binary 1 and a Zero-Width Non-Joiner might represent a binary 0. By varying which invisible characters appear between each word, a unique identifier can be embedded that survives copy-pasting. When the text later appears online, the original source can decode the hidden pattern and identify the specific user or account it was copied from.
Yes. Zero-width and other non-printing Unicode characters are a frequent source of hard-to-debug errors in software. If a developer copies a variable name, API key, URL, or JSON key from a webpage or PDF and a hidden character is present, the string will look correct in the editor but will fail string comparisons, key lookups, and URL parsing at runtime. Database queries can also fail silently if a primary key or field value contains an invisible character that was not present in the original schema. This tool lets you sanitize any pasted text before using it in code.
The detector iterates through every character in your pasted text and checks each character's Unicode code point value against a list of known non-printing characters. These include the range U+200B through U+200F (zero-width space, non-joiner, joiner, left-to-right mark, and right-to-left mark), as well as U+FEFF (the byte-order mark), U+2060 through U+2064 (word joiner and invisible math operators), and U+180E (Mongolian vowel separator). When a match is found, the tool inserts a labeled amber badge at the exact position in the output visualizer so you can see precisely where each hidden character was hiding.
Copied text from untrusted websites can carry hidden Unicode characters that range from harmless formatting artifacts to intentional tracking watermarks or even obfuscated code snippets designed to look like safe text. Best practice is to paste any copied text into this detector before using it in emails, documents, source code, or database fields. The Strip All Hidden Characters button removes every detected non-printing character and returns a clean string you can safely use anywhere.
Privacy Notice: This tool runs entirely in your browser. No text you paste is ever transmitted to any server or stored outside your current browser session. All character analysis, detection, and sanitization happens locally on your device.