Regex Tester

A regex tester is an interactive tool that runs a regular expression against sample text and shows you exactly what it matches, so you can debug a pattern without round-tripping through code. Regular expressions are compact but unforgiving: a single misplaced quantifier or a forgotten flag can silently change the result, which is why a live tester is worth far more than reading the pattern in your head. Xevon Tools' Regex Tester highlights matches in real time as you edit either the pattern or the test text, and it displays the total match count, each match's start position, and the value of every capture group. It exposes JavaScript's flags as individual toggles. The g (global) flag controls whether the engine finds one match or all of them, which is the single most common source of confusion. The i flag makes matching case-insensitive, m changes how the anchors caret and dollar behave so they match at each line break, and s (dotAll) lets the dot match newline characters too. The engine is JavaScript's native RegExp, the same implementation that ships in every browser and in Node.js, so a pattern you validate here behaves identically in front-end code, server code, or a build script. That also sets a boundary: JavaScript regex is not identical to Python's re module or to PCRE, so a pattern proven here may need adjustment for another language, particularly around lookbehind and some escape sequences. Typical uses include hardening a log-parsing pattern, testing form-validation rules against edge cases, building search-and-replace expressions with capture groups, and simply learning regex by experiment. Everything runs in your browser, so the sample text you paste, which is often real log output, stays private.