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Regex Tester

Test and debug regular expressions online with real-time match highlighting, capture groups, substitution replacer, and regex flag controls (g, i, m, s, u). Complete with helpful regex syntax cheatsheet.

Test and debug regular expressions online with real-time match highlighting, capture groups, substitution replacer, and regex flag controls (g, i, m, s, u). Complete with helpful regex syntax cheatsheet.

Regular Expression

Test String

Matches (0)

Enter regex pattern and test string to see matches

Common Regex Patterns

  • \d+ - One or more digits
  • [a-zA-Z]+ - One or more letters
  • ^[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,}$ - Email
  • https?://[^\s]+ - URL
  • \b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b - IP address
  • ^\d{4}-\d{2}-\d{2}$ - Date (YYYY-MM-DD)

How it works

  1. Enter your regular expression pattern
  2. Select flags (Global, Ignore Case, Multiline)
  3. Enter text to test against the pattern
  4. View all matches with their positions and groups

How to Use Regex Tester Online

  1. Enter regular expression: Input your regex pattern (e.g., [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}) and flags.
  2. Paste test string: Enter sample text or log files to test your pattern against.
  3. Inspect matching highlights: View matched groups, match counts, and capture indices in real time.

ClickBasic tools run 100% securely with zero installation, no registration, and no limits.

Key Features of ClickBasic Regex Tester

Live Match Highlighting: Visual colored highlights show exactly where your regular expression matches.
Regex Flag Toggles: Easily toggle Global (g), Case-Insensitive (i), Multiline (m), and DotAll (s) flags.
Capture Groups Breakdown: Examine numbered and named capture groups with exact string offsets.
Zero ReDoS Risk: Safely tests expressions in a sandboxed client environment.

Frequently Asked Questions

Enter an email pattern like ^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$ and test against valid and invalid email addresses in the test area.

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