This page finds U+2212 MINUS SIGN (the typographic minus that is not a hyphen) and converts it to ASCII "-". The sample below fails float parsing. Everything runs in your browser — nothing is uploaded.
The real typographic minus: same width as +, sits at the same height, looks better in math. It is also a completely different character from the ASCII hyphen-minus - (U+002D) that every programming language and parser expects for negative numbers.
Wikipedia and other well-typeset references use U+2212 for negative values, macOS Calculator copies results with it, weather sites use it for sub-zero temperatures, and scientific software (and LaTeX-rendered content) emits it. Copy any of those numbers and the minus rides along.
Number parsing everywhere: Python's float("−5.2") raises ValueError, JavaScript's parseFloat returns NaN, spreadsheets store the "number" as text so sums silently skip it, SQL inserts fail or store junk, and CSV imports flag the column as non-numeric. The error is baffling because the value looks exactly right.
Paste the numbers above — every minus sign (and nine other dash lookalikes) is highlighted and converted to a plain ASCII hyphen in the cleaned output. In your own code, a targeted text.replace("\u2212", "-") before parsing, or NFKC-based number normalization, fixes it at the source.
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