Regex Tester

About

Test, debug, and save regex patterns with real-time highlighting, group captures, and replace preview.

Regex Tester gives you a fast, in-browser regex testing tool right in your toolbar. No more switching to regex101.com — test patterns instantly without leaving your workflow.

How it works:

1. Click the extension icon to open the regex tester.
2. Type a regex pattern and set flags (g, i, m, s, u).
3. Paste or type your test string — matches highlight in real time.
4. See all matches with group captures in the results panel.

Features:

- Real-time matching — matches highlight as you type the pattern or test string.
- Flag toggles — click to enable g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode).
- Group captures — see numbered capture groups for every match.
- Replace mode — enter a replacement string and preview the result live.
- Quick reference — 20 common regex patterns (email, URL, phone, IP, date, etc.) with one-click insert.
- Save patterns — store frequently used patterns with labels for quick access.
- Match count — see how many matches were found at a glance.
- Copy results — copy matches or replaced text to clipboard.
- Error display — friendly error messages for invalid regex syntax.
- 100% local — no data leaves your browser. No accounts, no tracking, no servers.

Privacy:

Regex Tester does not collect, transmit, or share any data. Your saved patterns are stored locally using Chrome's built-in storage. No analytics, no telemetry, no third-party services.