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Quick recipes:
Matches: 0 (none)
Regex literal: / / · Time: 0.0 ms
Matches
Highlighted text
1
No matches yet.
Replace tester
Supports $1 and $<name>Replacement output preview appears here.
Split tester
Split results appear here.
Explain mode
Toggle on to see a quick token breakdown of the regex.
Test cases
Case #1
Status: No regex
How to use
- Enter a regex pattern and toggle flags (i/g/m/s/y/u) as needed.
- Paste your test text; matches highlight in the preview and list below.
- Use `Treat pattern as literal` to escape regex characters.
- Enable `Safe mode` to limit input size and block suspicious patterns.
- Try Replace and Split testers to validate transformations.
- Use Test cases to validate expected matches or replacement output.
- Use Prev/Next or click a match to jump to highlights.
- Shareable URLs keep pattern, flags, and text in the query string.
- Shortcuts: Cmd/Ctrl+Enter to run, Cmd/Ctrl+L to focus pattern, Esc to clear selection.
- Copy or download matches as JSON for quick debugging.
FAQ & privacy
Does this run locally? Yes, everything happens in your browser; no data is sent to a server.
Why do I see no matches? Make sure your pattern is valid and flags are set correctly; use the sample button to verify the workflow.
What does “Pattern too expensive” mean? The matcher exceeded the time budget; simplify the regex or reduce input size.
Can I test large text? Yes, but inputs over ~50k chars will show a warning to avoid slow runs.