Characters you can’t see, and why they matter
Unicode contains dozens of characters that take up no visible space or look exactly like an ordinary space. They slip in through copy and paste, word processors, websites and sometimes deliberately:
- Zero-width space, joiner and non-joiner, word joiner and BOM: break searches, password and username matching, code, and spreadsheet formulas.
- No-break and other special spaces: look normal but don’t match a regular space.
- Bidirectional controls (RLO, LRE, isolates) can make text display in a different order from how it’s stored. In source code this was exploited in the 2021 “Trojan Source” attacks; in file names it can disguise an extension.
- Unicode tag characters (U+E0000–E007F) are invisible copies of ASCII letters. Researchers have shown they can hide instructions inside text that people can’t see but AI chatbots do read (“ASCII smuggling”). This tool decodes any hidden tag message so you can see it.
- Hangul and Braille fillers, variation selectors, control characters and private-use characters.
Safe removal
Some invisible characters are legitimate. Removing them blindly breaks things:
- Zero-width joiners and variation selectors are part of emoji like 👨👩👧 and ❤️, kept by default.
- The zero-width non-joiner is required for correct spelling in Persian and several Indic scripts (kept by default when those scripts are present).
- Tag characters are part of the subdivision flags of England, Scotland and Wales, kept inside those flags.
Everything else is removed, and special spaces become normal spaces. Copy or download the cleaned text from the results panel.
Worked example
Here is what the Invisible Character Detector returns for its built-in example. Settings used: Keep joiners inside emoji: on; Keep ZWNJ in Persian/Indic text: on; Keep no-break spaces: off. Click Try an example in the tool above to load it, then change it as you like.
Helloworld — copypaste from a website. Family: 👨👩👧. Priceevil. Hidden: end.| Result | Value |
|---|---|
| Hidden characters | 36 |
| Suspicious | 33 |
| Kinds | 21 |
| Hidden tag text | Yes |
Questions
How do I find zero-width spaces in text?
Paste the text. Every invisible character is shown as a labelled tag (ZWSP, NBSP, RLO…) in place, with a table of what was found.
What is ASCII smuggling?
Hiding text in invisible Unicode tag characters. People cannot see it, but software (including AI models) can read it. This tool decodes and removes such hidden text.
Will removing invisible characters break emoji?
No. Joiners and variation selectors inside emoji are kept by default.
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