RegEx Tester

Test and validate your regular expressions.

//
Test String
Match Preview

Test and debug Regular Expressions in real-time. Visualize matches locally without server lag.

Why This Tool Exists

Regular Expressions (RegEx) are often called a "write-only" language. They are incredibly powerful for pattern matching, but one missing escape character or bracket can break your entire application. Testing Regex usually involves writing a script, running it, and iterating. PrivaQuickTools allows you to paste your pattern and your text, and see matches highlight instantly as you type. Because regex engines vary (PCRE vs JS vs Python), we explicitly use the JavaScript engine. This is perfect for web developers and Node.js engineers.
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I deployed a form validator that rejected email addresses with "plus" signs because I missed a single character in my regex. A visual tester would have caught that edge case immediately.

Key Capabilities

Core features that make this tool powerful.

Privacy First: Files never leave your device.

Instant: No upload or download wait times.

Secure: Local processing guarantees data safety.

Free: No subscriptions or hidden fees.

How It Works

Understanding the processing logic.

A real-time JS Regex engine interface: - **Flags:** Toggle global (g), case-insensitive (i), multiline (m). - **Groups:** Highlights capturing groups (parentheses) visually. - **Performance:** Runs at native browser speed.

Accuracy & Reliability

Standard browser-based processing logic.

Who Is This For?

Web Developers

Validate form input patterns (email, phone, dates).

Data Scrapers

Extract specific tokens from unstructured text blobs.

Common Mysteries & Fixes

Engine Differences

This tool uses JavaScript's Regex engine. Features like 'Lookbehind' are supported in modern browsers but might not work in older Python/PHP versions.

ReDoS

Catastrophic backtracking can freeze your browser if you write an inefficient recursive pattern.

Real-World Scenarios

Quick Processing

Process files without verifying server security.

Offline Work

Use the tool without an internet connection.

Why Choose PrivaQuickTools

FeaturePrivaQuickToolsOthers
Privacy100% LocalCloud Upload
CostFreeFreemium
SpeedInstantSlow Uploads
RegistrationNoneRequired

Privacy & Security Guaranteed

We do not store, view, or upload your files. All processing happens in your browser's memory. When you close the tab, all data is wiped from memory.

Good to Know

Large files depends on your device RAM. Processing massive video/PDFs may be slower on mobile devices.

Benefits

  • Local ProcessingData stays on your machine, always.
  • No InstallationWorks instantly in your browser.
  • Zero Cost100% free and open.
  • UnlimitedNo artificial limits on file count.

When Not To Use

While we aim for perfection, browser-based tools have limits. This tool might not be the best fit for:

  • Extremely large files (e.g., video over 2GB)
  • Batch processing thousands of files at once
  • Workflows requiring server-side collaboration or cloud storage

Frequently Asked Questions

Common questions about this tool.

Yes, if your browser supports ES2018+ (most modern Chrome/Firefox/Edge do).
Use the 's' (dotAll) flag or [\s\S] hack depending on your target environment.