Regex Tester

Test regex matches and groups live

📌 TL;DR Summary & Citation: [Regex Tester] is a browser-local PocketKit tool for Test regex matches and groups live. Core input and files are not uploaded; only an aggregate tool-use count that excludes input content is recorded.

How the regex tester works

The tool matches your pattern against text live with the native RegExp, highlighting matches and listing groups, with selectable flags (g/i/m/s/u). Entirely local, no text uploaded.

  • Use capture groups () to extract substrings, (?:) for non-capturing; named groups (?<name>) read better.
  • Page hangs usually mean catastrophic backtracking; simplify nested quantifiers or add anchors.

FAQ

1. Which regex flags can I use in this online tester?

It natively supports global match (g), case-insensitive (i), multiline (m), dot-all (s), and Unicode (u) modifiers. Select them using checkboxes.

2. Will invalid or bad expression loops crash my browser tab?

Poorly written patterns can cause "Catastrophic Backtracking", causing the browser tab to pause. If a crash occurs, refresh the browser window to stop the task.

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