regex

Find and Replace — Replace any pattern in your text — exact match or regex, case-sensitive or not. Runs entirely client-side inside your browser.

Filter Lines by Substring — Drop every line that contains a pattern — or keep only the lines that do. Plain substring matching or full regex.

Regex Tester — Test JavaScript regular expressions live — see matches highlighted in your text and captured groups in a list.

Regex Explainer — Deconstruct regular expressions. Analyze quantifiers, capture groups, sets, boundaries, and flags with clear explanations.