Find and Replace

Find and replace is one of the most reached-for text operations there is, but a plain literal search misses a lot of real-world cases: you might need a case-insensitive match, a match that only counts when the search term is a whole word (so replacing "cat" doesn't also touch "category" or "scatter"), or a pattern-based match that covers many variations at once (any phone-number-like sequence, any line starting with a number, and so on). This tool covers the full range from simple literal replace up to full regular-expression find-and-replace, in one interface. By default, the Find field is treated as a literal string: whatever you type is matched exactly as written, including any characters that would otherwise have special meaning in a regular expression (like `.`, `*`, `(` or `[`). Internally, this is implemented by escaping every regex metacharacter in your search term before using it — so searching for a literal `3.14` will not accidentally also match `3x14` the way an unescaped `.` (which means "any character" in regex) would. Turning on "Use regex" removes that escaping step and passes your Find text directly to JavaScript's `RegExp` engine as a pattern, unlocking everything from character classes (`[0-9]+`) to alternation (`cat|dog`) to capture groups you can reference in the Replace field using `$1`, `$2`, and so on — a genuinely powerful feature for anyone comfortable with regex syntax, and completely optional for anyone who is not. "Whole word only" wraps whatever pattern is being used — literal or regex — in `\b...\b`, the regex word-boundary anchor, so a search for `cat` only matches `cat` as a standalone word and does not also match the `cat` inside `category`, `scattered`, or `concatenate`. This combines with both literal and regex mode: turn it on with a literal search for precise whole-word matching, or combine it with a regex pattern for a more targeted match. "Case-sensitive" defaults to off (so `Hello` and `hello` are treated as the same match) and, when turned on, requires an exact case match. The match count updates live as you type in either the source text or the Find field, or as you toggle any of the three options — so you always know exactly how many replacements Replace All is about to make before you commit to it, without needing to click a separate "preview" button. If your Find text is not valid as a regular expression — an unclosed bracket, an invalid quantifier, and so on — this only matters when "Use regex" is on (a literal search is always automatically escaped into something valid), and the tool catches the resulting error from the `RegExp` constructor and shows it inline in red rather than letting an uncaught JavaScript exception silently break the page; the match count simply reads zero until the pattern is fixed, and if you already had a previous successful Replace All result on screen, it stays there untouched rather than being wiped out by the new error. Replace All never modifies your original source text — the replaced text always appears in a separate, clearly labeled result box below, so you can compare before and after, run a different find/replace pass starting from the same original text, or simply copy the result out once you're happy with it via the one-click Copy button.