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Regex Tester
Test a regular expression against your own text — the browser's own engine, every match listed, runs in a disposable worker.
The browser’s own RegExp — what you test is what your page ships · every run in a disposable worker
Valid flags: d g i m s u v y — no duplicates, and u/v are mutually exclusive.
No run yet.
- The browser’s own RegExp runs the pattern — no engine substitution, so behavior (including lookbehind, named groups, v-mode set notation) is exactly what your page ships.
- A native RegExp cannot be interrupted, so every run executes in a disposable worker: a pattern that backtracks catastrophically is terminated at the 5-second deadline and reported — never a frozen tab, never a silent retry in the page. Environments without workers refuse to run it at all.
- Matches list the way matchAll does: the global flag is implied for listing, and zero-length matches advance by one so they are all reported, never dropped.
- Caps, stated before you hit them: 1,000 listed matches (the TRUE total always shows), 32 listed groups per match, 1,000,000 test-text bytes, 1,000 pattern characters.
Nothing in yet
Paste, drop, or type to begin. Everything stays on this device.
the d flag adds [start, end) spans to every group