Regex Tester
Test a regex pattern and see every match and capture group
calendar_today Last updated: September 17, 2026
2 matches
2026-09-17at 71:20262:093:172026-10-02at 281:20262:103:02
Run in your browser — your pattern and text stay on this page.
Sahel's regex tester shows every match with its position and capture groups, named ones included, with the usual flags and a replace box, and runs in your browser.
help_outline
How does this tool work?
1
Write the pattern
A half-typed one is reported quietly, not thrown at you.
2
Pick the flags
Ignore case, multiline, and the rest.
3
Read the matches
Each match with its position and groups, plus an optional replace box.
Frequently asked questions
Why no red error while I am typing the pattern? expand_more
Because an incomplete pattern is a normal state mid-edit, not a failure. A quiet note appears and disappears the moment the pattern is complete, rather than an alert shouting on every keystroke.
What are named groups for? expand_more
They let you refer to a captured part by name rather than number, which keeps both the pattern and the replacement readable and stops them breaking when you add a group in the middle.
Why is there a length limit on the input? expand_more
Because some patterns backtrack catastrophically on long text, and there is no way to interrupt a running regular expression. The limit is what stops the page freezing.
Will these patterns behave the same in my language? expand_more
The core syntax is shared across most languages, but details differ — flags, group syntax, a few escapes. Treat the result here as strong evidence and confirm it in your own environment before relying on it.
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