Regex Performance Tester

Measure one bounded browser sample without treating its timing as a guarantee for other browsers, inputs, engines, or adversarial strings.

Pattern

Flags

Sample text

Iterations

Hard timeout

Static warning

—Total ms

—ms / operation

—Matching runs

—Iterations

ReadyA timeout can stop this sample probe, but no finite test can prove a regex safe or fast for every possible input.

Before reusing a regular expression

keeps the established regex widgets and worker-guarded execution paths intact while connecting testing, explanation, extraction, replacement, test cases, static risk review, and code generation. Pattern data stays in the browser, and the shared inspector can save an explicit pattern locally.

Regex flavor and performance boundaries

Interactive checks follow the JavaScript RegExp implementation available in the current browser unless a tool explicitly says otherwise. Token explanations and backtracking warnings are bounded static guidance, not PCRE/Python/.NET compatibility, formal complexity analysis, or proof that a pattern is safe for every possible input.