Regex Tester Online Free
Test and debug regular expressions online. Input a regex pattern, configure flags (global, case-insensitive, multiline), and check matches and capture groups on live test strings instantly.
✓ Free IT tool✓ No signup required✓ Fast results✓ Browser-based utility✓ Mobile friendly
Regex Pattern
Flags
Test String
This tool runs in your browser and does not upload data to BuBird servers.
How To Use
How to Use Regex Tester
1
Enter Regex Pattern
Type your regular expression pattern (e.g. ^[a-zA-Z]+$) into the expression input box.
2
Configure Flags
Select options such as Case-Insensitive (i), Global (g), or Multiline (m) flags.
3
Provide Test Text
Type or paste your test text in the area below. Matching strings highlight instantly.
4
Inspect Matches & Groups
Review the capture groups and match details to verify your regex logic works correctly.
Example
Example Use
Validating Email Formats using Regex
You need a pattern to validate email addresses. Input the regex pattern ^[^@\s]+@[^@\s]+\.[^@\s]+$ and enter various email strings (e.g. contact@example.com, invalidemail) in the test field. The correct strings highlight in green while invalid formats show no match.
Use Cases
Who Uses Regex Tester
Web Developers
Validate user input formats (emails, phone numbers, postal codes) before writing frontend code.
DevOps Engineers
Build regex patterns to filter log files, grep logs, and configure server rules.
QA Engineers
Test test cases and verify data extraction patterns for test scripts.
IT Students
Learn regular expression syntax, capture groups, boundaries, and quantifiers.
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FAQ
Frequently Asked Questions
What is a regular expression?
A regular expression (regex) is a sequence of characters that forms a search pattern, mainly used for pattern matching and text parsing within string operations.
How does live regex matching work here?
The tool uses JavaScript's built-in RegExp engine. As you edit your expression or target text, the matcher highlights matching characters instantly.
Are my test strings uploaded?
No. Testing and matches execute locally in your web browser. No data or strings are sent to BuBird servers.