Tools · Developer Tools
Regex Safety & Performance Inspector
Flag common backtracking traps, then test a sample in a worker that is killed if it runs too long.
Heuristic review
Matches
The worker is terminated if matching exceeds 800 ms. This does not prove a pattern is safe in every engine.
How it works
- Enter a pattern. Inspect for nested quantifiers and unbounded wildcards.
- Paste a sample and test. Matching runs off the UI thread.
- Cancel if you need to stop. The worker is terminated.
FAQ
Can this freeze my browser?
The test is designed not to. The worker is killed after a short timeout. Inspect-only does not execute the pattern against a large sample.
Is my sample uploaded?
No. Pattern and sample stay in this browser.
Read the original guide: Test a regex without freezing the tab.