Small ToolsAll tools
← All tools / Regex
Regex utility

Regex Replace Tester

Preview JavaScript regular expression replacements on sample text.

● This tool runs entirely in your browser. Your input is never uploaded to our servers.

Use short sample text. Complex patterns can take a long time to run.

Output
Your result will appear here…

How to use Regex Replace Tester

  1. Enter a JavaScript regex pattern and flags.
  2. Enter replacement text; $1 and $& groups are supported.
  3. Paste sample text and select Replace to preview the result.

Example

Input:

user_123, user_456

Output:

Pattern: user_(\d+)
Replacement: account-$1
Result: account-123, account-456

Use cases

About this tool

Preview JavaScript regular expression replacements on sample text. Processing happens locally in your browser, so your input is not sent to a server or included in analytics.

Frequently asked questions

Are capture groups supported?

Yes. JavaScript replacement tokens such as $1 and $& are supported.

Does the global flag replace all matches?

Yes. Add g to replace each match; without g only the first match is replaced.

Is replacement done on a server?

No. The browser applies the replacement locally.

Related tools