Regex Tester
Test regex patterns and view match results.
About this tool
This tool tests regex patterns in real time. Three features: 1) Enter pattern and test text for instant match results, 2) Supports g (global), i (ignore), m (multiline) flags, 3) All processing in browser—no data sent to server. Ideal for validation pattern verification.
Tool interface
Usage
- Enter regex pattern and test text
- Select g (global), i (ignore), m (multiline) flags
- Match results and indices are displayed in real time
When to use
Verifying regex behavior, testing validation patterns, checking extraction patterns for logs.
Examples
[a-z]+ for lowercase, \d{4}-\d{2}-\d{2} for date, ^[\w.-]+@[\w.-]+\.\w+$ for email.
FAQ
What is regex?
Pattern notation for strings. Used for validation, search/replace, log extraction.
What is the g flag in regex?
Global—match all occurrences, not just the first. Without g, only first match is returned.
Regex for email validation?
Simple: ^[\w.-]+@[\w.-]+\.\w+$. Full validation is complex; prefer a library for production.
What does \d mean in regex?
One digit (0-9). \d{4} = 4 digits, \d+ = one or more digits.
Is Regex Tester free?
Free to use, no sign-up required.
Is data sent to a server?
Data stays on your device; we do not store it on our servers.
Supported browsers?
Tested on recent Chrome, Edge, Firefox, and Safari.
Offline use?
Core features work offline after the first load.
vs CLI or desktop apps?
Regex Tester is an install-free online alternative to CLI or desktop apps.
When to use it?
Use it when: Verifying regex behavior, testing validation patterns, checking extraction patterns for logs.
Usage example?
Example: [a-z]+ for lowercase, \d{4}-\d{2}-\d{2} for date, ^[\w.-]+@[\w.-]+\.\w+$ for email.
Main features?
Real-time match results, g/i/m flags, Match indices display
How is this different from similar tools?
Regex Tester runs in the browser with no install—ideal for quick checks before heavier CLI or IDE workflows.
Search keywords
正規表現, regex, パターン, バリデーション, マッチ, 正規表現 テスト
Basic workflow
- Enter regex pattern and test text
- Select g (global), i (ignore), m (multiline) flags
- Match results and indices are displayed in real time
Practical use cases
- Verifying regex behavior, testing validation patterns, checking extraction patterns for logs.
- This tool tests regex patterns in real time. Three features: 1) Enter pattern and test text for instant match results, 2) Supports g (global), i (ignore), m (multiline) flags, 3) All processing in browser—no data sent to server. Ideal for validation pattern verification.
- Real-time match results
- g/i/m flags
Privacy & data handling
Data stays on your device; we do not store it on our servers.
Things to watch out for
- Always double-check before pasting output into production
- Try incognito if extensions break the page
- Wait for processing on large inputs