Free Regex Tester Online
Test regular expressions instantly using browser-based JavaScript regex validation. Supports live matching, flags and match highlighting. No text is uploaded or stored.
What is a Regular Expression?
A regular expression (regex) is a text pattern used for searching, matching and validating strings. Regex is commonly used in programming, validation systems and text processing.
Regular expressions allow developers to detect patterns such as emails, phone numbers, usernames and custom formats.
Supported Regex Flags
- g — Global matching
- i — Ignore case
- m — Multiline matching
- s — Dotall mode
- u — Unicode support
Live Regex Matching
This regex tester highlights matching text directly in your browser, making it easier to debug and validate patterns.
Browser-Based Privacy
All regex testing happens locally in your browser. No patterns or sample text are uploaded to servers.
Common Regex Use Cases
- Email validation
- Password validation
- URL matching
- Search and replace workflows
- Data extraction and parsing
Related Tools
JSON Validator, Base64 Encoder, URL Parser, Code Formatter
Frequently Asked Questions
What is a regular expression?
A regular expression is a pattern used for matching and validating text.
What regex flags are supported?
This tool supports standard JavaScript regex flags including g, i, m, s and u.
Does this tool upload text?
No. All regex testing happens locally in your browser.
Can I highlight multiple matches?
Yes. Global matching allows highlighting all matching text segments.