What Are Invisible Characters and Why They Matter

Published: November 24, 2025

Invisible characters are Unicode code points that have no visible width or glyph but still exist in text. They include zero-width spaces, joiners, directional marks, and byte order marks (BOMs). While harmless in some contexts, they are frequently used maliciously or accidentally introduced via copy-paste.

The Most Common Invisible Offenders

U+200B — Zero Width Space (ZWSP)
U+200C — Zero Width Non-Joiner (ZWNJ)
U+200D — Zero Width Joiner (ZWJ)
U+FEFF — Zero Width No-Break Space / BOM
U+2060 — Word Joiner
U+00A0 — Non-Breaking Space (often copied from web pages)

Real-World Damage

These characters cause real problems:

JSON fails to parse with “Unexpected token” errors
Code looks correct but throws syntax errors
Discord/Slack messages appear empty but trigger spam filters
Clipboard poisoning attacks that spread invisible payloads
Git diffs polluted with invisible changes

Why This Tool Was Built

Most online cleaners are slow, send your data to servers, or miss advanced Unicode ranges. This scanner runs 100% in your browser, detects everything instantly, and respects your privacy completely — as required by NFR-03 and NFR-06 in the SRS.

FAQ

Can invisible characters be used in phishing?

Yes. Attackers use ZWJ/ZWNJ to create visually identical domain names or usernames (homograph attacks).

Why not just use regex find/replace?

Most editors can’t display or select invisible characters reliably. This tool highlights them visually and removes them in one click.

Is it safe to paste sensitive code?

Yes — nothing ever leaves your browser. No logs, no tracking, no backend.

Protect your text. Scan everything. Stay invisible-character-free.