How do I reference capture groups in the replacement?

Use $1, $2 and so on for numbered groups, $& for the entire match, and $$ for a literal dollar sign — the same syntax as JavaScript String.replace.

What do the flags do?

Global (g) replaces every match instead of just the first; ignore-case (i) makes matching case-insensitive; multiline (m) makes ^ and $ match line boundaries; dotall (s) lets the dot match newlines.

Is my text uploaded anywhere?

No. The regular expression runs through your browser's built-in JavaScript engine, so your pattern and text stay on your device.

Why does only the first match get replaced?

Without the global flag, regex replace stops after the first match. Turn on the global (g) flag to replace every occurrence in the text.

Can I use named groups or lookbehind?

Yes, the tool uses the modern JavaScript regex engine, so named groups (? ...), lookahead, and lookbehind are supported in patterns. In the replacement you can reference numbered groups with $1, $2 or named groups with $ .

What does the match count tell me?

It shows how many times the pattern matched the input, which is a quick way to confirm your expression is hitting the intended spots before you trust the replaced output.

My pattern is not matching — what is wrong?

Common causes are forgetting to escape special characters (. + * ? etc.), missing the global flag for multiple matches, or needing the multiline (m) flag for ^ and $ to match line boundaries. Adjust the flags or escape the literals.

Regex Replace Tool — Gera Tools

A focused regex find-and-replace tool: enter a pattern, a replacement string, pick your flags, and watch the substituted output update live. Capture-group references let you reorder and reshape matched text — ideal for reformatting dates, cleaning data, bulk-editing code, and one-off text transformations.

How it works

The tool builds a JavaScript RegExp from your pattern and the flags you select, then runs String.replace against your input. In the replacement string you can use the standard substitution tokens: $1, $2 for the first, second numbered capture group, $& for the whole match, $<name> for a named group, and $$ for a literal dollar sign. The flags control matching: g (global) replaces every match instead of just the first, i ignores case, m (multiline) makes ^ and $ match at line breaks, and s (dotall) lets . match newlines. A live match count confirms how many replacements were applied.

Example

Reformat ISO dates to day/month/year. With the global flag on:

Find: (\d{4})-(\d{2})-(\d{2})
Replace: $3/$2/$1
Input: 2026-05-28
Output: 28/05/2026

Token	Meaning
`$1`, `$2`	Numbered capture groups
`$&`	Entire match
`$<name>`	Named capture group
`$$`	Literal `$`

Patterns use the standard JavaScript engine, so what works here works in your code. Nothing is uploaded; all matching happens in your browser.