Invisibles

What goes wrong

One invisible character kept a PlayStation trophy stuck at 99.8% for ten years. The same kind of character breaks CSV and JSON imports, stops a password from matching when it looks identical, and throws off code search. Text pasted out of an AI often carries a few of them too, like the narrow no-break space at U+202F. Your editor doesn't draw any of it, so you usually find out only after something breaks.

What it looks for

Zero-width characters

Zero-width spaces and joiners, the word joiner, the byte-order mark. Completely invisible, and the ones that quietly break search and passwords.

Spaces that aren't spaces

Non-breaking space, the narrow no-break space, ideographic and thin spaces. They look like a normal space and aren't one.

Direction controls

Right-to-left overrides and isolates. These can reorder text on screen so it reads differently from what's stored, which is the basis of the Trojan Source trick.

Tag characters and variation selectors

Invisible characters that can smuggle a hidden message, prompt, or watermark inside ordinary-looking text.

Fake spaces get turned back into a normal space so words don't run together. Everything else is removed. If you tick the box, it also swaps the fancy punctuation (curly quotes, em dashes, ellipsis) for plain ASCII, which is handy when you're scrubbing the typographic giveaways out of AI text.

It doesn't upload anything

Most tools for this are websites you paste into, which means your text lands on their server first. This one has no server. It's a single page and one small script you can read in a couple of minutes. Works offline, and it's free.

Source on GitHub if you'd rather run it yourself, or grab the browser extension so it's a click away from any tab.