The expression runs in a separate Worker and is terminated if execution takes too long.
.* Developer workbench
Regex Tester
Debug regular expressions in real time with exact ranges, capture groups, replacement preview, pattern explanation, and ready-to-use code — without freezing the tab.
Runs locallyYour pattern and test data stay in the browser
Quick start
Ready-made cases
02 · TEST STRINGTest string
0 chars · 1 line03 · RESULTResult
Ready
No matches
Replacement result
How this expression readsSteps follow the actual matching order, including groups and alternatives.
Use it in codeReady-to-use snippets for popular languages.
CHEAT SHEET
Regex cheat sheet
Click a construct to insert it at the current caret position.
REGEX LAB
How to Use the Tester
Enter a regular expression in the pattern field (without delimiter characters / /), select the desired flags, and paste the test text. All matches will be highlighted in the text, and a list with capture groups will appear below. The g (global) flag finds all matches, i — ignores case, m — multiline mode, s — allows dot to match newlines.
Every match includes indices, line, column, and named capture groups.
Test replacement templates with $1 and $<name> before moving them into code.
Free online regular expression tester with real-time match highlighting. Enter a pattern and test text — the tool instantly finds all matches and highlights them directly in the text. All major flags are supported: global search (g), case-insensitive (i), multiline (m), and dotAll (s).
Regular expressions (regex) are a powerful tool for searching, validating, and processing text data. They are used in programming, system administration, log analysis, data parsing, and many other fields. Capture groups — both named and numbered — are displayed for each match, helping you understand match structure.
The match counter shows the total number of results found. The tool automatically handles pattern errors and displays a clear error message. Perfect for developers writing and debugging regular expressions for email, phone, and URL validation, HTML parsing, and string processing.