DEV
Free Developer tool

Regex Tester

Test a regular expression and inspect every match.

Private by design

The working input is processed in this browser and is not stored by 247888.

About this tool

What does Regex Tester do?

Test a regular expression and inspect every match. The workspace keeps the input and result together, making it easy to check the change before you use it elsewhere.

For example, you can test a regular expression and inspect every match when checking a value copied from logs.

What you can control

Regex Tester gives you direct control over regular expression and flags.

How to use Regex Tester

  1. 1

    Paste or type the test text you want to work with.

  2. 2

    Set regular expression and flags to match the result you need.

  3. 3

    Run Regex Tester, review the output, then copy or download it where available.

Tips for a better result

  • Keep the source test text beside the Regex Tester output so you can check the transformation.
  • Change one setting at a time—especially regular expression—so differences are easier to compare.
  • Treat decoded or formatted output as data, not proof that the source is safe or authentic.

Frequently asked questions

Is my input private when I use Regex Tester?+

Regex Tester handles the pasted value locally in this browser. Avoid using real production secrets on an untrusted or shared device.

What should I check after using Regex Tester?+

Treat decoded or formatted output as data, not proof that the source is safe or authentic.

Try “make image smaller”, “jpg into pdf”, “pretty json” or “count my words”.