Regex Escape Tool

How it is calculated

The tool walks through your text one byte at a time and puts a backslash in front of every character from this fixed list: . ^ $ * + ? ( ) [ ] { } | \ /. Everything else is copied unchanged, including letters, digits, spaces, accented letters and emoji. The slash is on the list even though it is only special inside JavaScript regex literals. The hyphen - and the hash # are not escaped, so a hyphen inside a character class such as [a-z] still keeps its range meaning. The output also reports how many characters were escaped and the length of the original text counted in characters, not bytes. Empty text shows no result, while text made only of spaces is returned as it is. The result is intended for PHP, Python, JavaScript and similar engines, but check the flavour you use.

Common mistakes

• Assuming the hyphen is escaped. It is not, so if you place the output inside a character class such as [...], escape any hyphen yourself or put it first or last.
• Escaping the same text twice. Running the output through the tool again doubles every backslash, which then matches a literal backslash followed by the character.
• Pasting the result into a language string without doubling the backslashes. In a normal Java, C or JavaScript string literal, \. must be written \\. unless you use a raw string.
• Using the output for the replacement side of a find-and-replace. Only the pattern side needs this escaping; replacement strings follow different rules (such as $1).
• Expecting whitespace, newlines or the hash to be treated specially. They pass through unchanged, so in free-spacing mode (where spaces and # have meaning) you must escape them yourself.