Find & Replace

about this tool

Plain text or a pattern

By default the search box is literal: what you type is what is matched, and regular expression characters like . and ( have no special meaning. Turn on regex and the box becomes a JavaScript regular expression, with matches highlighted in the text as you type so you can see what a pattern catches before you replace anything.

To work a pattern out before replacing with it, the regex tester uses the same engine and shows every match and group as you type.

Capture groups in the replacement

With regex on, $1, $2 and so on in the replacement field insert what the corresponding bracketed group matched. This is what turns find-and-replace into a reformatting tool. Given:

Ada Lovelace, born 1815

the pattern (\w+) (\w+), born (\d{4}) with replacement $3: $2, $1 produces:

1815: Lovelace, Ada

That one mechanism reorders a name column, rewrites a date format, or converts a list of URLs into Markdown links. $& inserts the whole match, and $$ inserts a literal dollar sign.

The flags, and what they actually do

Global replaces every occurrence rather than only the first. On by default, because replacing one is rarely what anyone wants.

Ignore case matches regardless of capitalisation. Note that the replacement does not adapt — replacing "cat" with "dog" turns "Cat" into "dog", not "Dog".

Multiline changes what ^ and $ mean: with it on they match the start and end of each line, with it off only the start and end of the whole text. If you are anchoring a pattern to a line, you need this.

Dot matches newline lets . cross line boundaries. Off by default, because a pattern like <div>.*</div> with it on will happily swallow your entire document.

Check before you commit

Matches are counted and highlighted before replacement, so the count is worth a glance: if you expected six and the tool says four hundred, the pattern is broader than you think. Everything runs in the page, so working on a document you should not upload is fine.

questions

How do I reorder text with find and replace?

Turn on regex and use capture groups. The pattern (\w+) (\w+), born (\d{4}) with replacement $3: $2, $1 turns 'Ada Lovelace, born 1815' into '1815: Lovelace, Ada'. Each bracketed group is available as $1, $2 and so on.

What does the multiline flag change?

It changes what the anchors mean. With multiline on, ^ and $ match the start and end of each line; with it off they match only the start and end of the whole text. You need it on to anchor a pattern to a line.

Why does my pattern match far more than expected?

Usually the dot-matches-newline flag combined with a greedy quantifier. A pattern like <div>.*</div> will swallow the whole document once the dot can cross line breaks. The match count is shown before you replace, so a surprising number is a warning.

Does ignore case adapt the replacement text?

No. Matching ignores capitalisation but the replacement is inserted exactly as typed, so replacing 'cat' with 'dog' turns 'Cat' into 'dog' rather than 'Dog'.

Can I use it on text I should not upload?

Yes. Matching and replacing both run in your browser and nothing is transmitted, so working on a confidential document is fine.