This page finds why copied code won’t run: zero-width spaces, smart quotes, em dashes and non-breaking spaces are flagged character-by-character and fixed. The sample below contains three classic failures. Everything runs in your browser — nothing is uploaded.
When code copied from a blog post, tutorial, PDF, Stack Overflow comment or chat message refuses to run, the cause is almost always a character that renders exactly like the one you expected: a zero-width space inside an identifier, curly quotes where the language wants straight ones, an em dash where a CLI flag wants --, or a non-breaking space that the shell refuses to treat as a separator.
Python: SyntaxError: invalid non-printable character U+200B or invalid character '“' (U+201C). JavaScript/Node: SyntaxError: Invalid or unexpected token. Go: invalid character U+200B. Bash: command not found (the command is fine — the space before it isn't a space). npm/curl/git: unknown option for a flag that is spelled correctly but starts with an em dash instead of two hyphens.
Paste the failing snippet above. The x-ray marks every suspicious character with its Unicode name — you'll usually spot the culprit in seconds — and the cleaned output has quotes straightened, dashes converted to hyphens, exotic spaces regularized and invisibles removed, ready to paste back. One caveat: an em dash becomes one hyphen; long CLI flags want two, so check flags after cleaning. To catch these in your editor instead, VS Code highlights invisible Unicode by default (editor.unicodeHighlight).
Guides for the common cleanup jobs — what the source puts into your text, exactly what it breaks, and the tool preloaded with a demonstration:
AI-generated text · Text copied from Word / Google Docs · Text copied from a PDF · Pasted code that won’t run · CSV & spreadsheet data · Invisible watermarks · Many files at once (batch)
Dedicated pages for the usual suspects — what each one is, where it sneaks in from, the exact errors it causes, and how to find it in your editor:
Zero-width space (U+200B) · Non-breaking space (U+00A0) · Byte order mark (BOM) (U+FEFF) · Soft hyphen (U+00AD) · Smart quotes · Em dash (U+2014) · Narrow no-break space (U+202F) · Ideographic space (U+3000) · Zero-width joiner (U+200D) · Zero-width non-joiner (U+200C) · Word joiner (U+2060) · Right-to-left override (U+202E) · Left-to-right mark (U+200E) · Line separator (U+2028) · Variation selector-16 (U+FE0F) · Object replacement character (U+FFFC) · Hangul filler (U+3164) · Braille pattern blank (U+2800) · Ligatures · Minus sign (U+2212)
Страницы на русском — те же инструменты с переведёнными правилами и примерами под задачу:
Невидимые символы в тексте · Убрать невидимые символы · Почистить текст нейросети · Неразрывные пробелы в числах · Текст из Word · Код не запускается