Regex Tester
Test JS regex with all flags, see index/groups. Simple presets included.
Regex tester
Summarizing the regular expression playground until it becomes interactive in the browser.
About this tool
The Gearizen Regex Tester gives developers and QA engineers a safe sandbox for crafting JavaScript regular expressions. Paste sample text, type your pattern, and instantly see matches, capturing groups, and named groups with syntax highlighting. Toggle flags like global, multiline, or case-insensitive to understand how each setting changes results. Because everything runs in your browser, proprietary logs, user data, or configuration snippets stay secure while you experiment with complex expressions.
This page is rich with educational content covering regex fundamentals, advanced techniques, and debugging strategies. Learn how lookaheads, lookbehinds, and backreferences work, when to escape special characters, and how to optimize patterns for performance. Troubleshooting guides help you avoid catastrophic backtracking, test edge cases, and translate regex between programming languages. With keyboard shortcuts and copy helpers, you can iterate quickly as you refine your pattern.
SEO-friendly sections address questions like "How do I test a regex?" or "Why doesn't my regex match?" We walk through real examples for email validation, log parsing, and data cleansing. Accessibility tips ensure the tester is usable with screen readers, while collaborative advice explains how to document patterns for teammates. Whether you're preparing to deploy a new validation rule or teaching a workshop, this resource delivers the context needed to use regex safely and effectively.
Round out your text processing toolkit with related Gearizen tools such as the Text Stats counter for measuring input size, the JSON Formatter for structured data testing, and the Case Converter for adjusting example strings. Bookmark the Regex Tester whenever you need precise pattern matching, shareable examples, or SEO-optimized guidance on mastering regular expressions.
Advanced tutorials dive into building reusable pattern libraries, integrating regex tests into CI pipelines, and collaborating on pattern reviews. These sections transform the tool into a training hub that elevates your team's text processing expertise. Pair the lessons with cheat sheets and you'll maintain consistent regex quality across every project.
How to use
Enter your sample text
Paste logs, payloads, or sentences that you want to match.
Write or paste your regex
Compose the pattern and toggle flags such as global or multiline.
Review matches and groups
Inspect highlighted matches along with capturing group details and indices.
Iterate and share
Adjust the pattern, copy results, and document the final regex for teammates.
Examples
| Scenario | Input | Output | Notes |
|---|---|---|---|
| Email validation | Pattern: ^[\\w.-]+@[\\w.-]+\\.[A-Za-z]{2,}$ | Matches valid email addresses | Quickly test variations before deploying. |
| Log parsing | Pattern with named group (?<status>\\d{3}) | Capturing group for status code | Extracts HTTP status from logs. |
| Bulk replace planning | Pattern using lookbehind | Highlights precise match positions | Ensures replacements target the correct substring. |
Help & FAQ
g flag?
We iterate all matches; you can toggle other flags.
Named groups?
If your pattern uses (?<name>...), named groups are listed per match.