Regex Lookahead & Lookbehind Tester

Lookaheads and lookbehinds are zero-width assertions that match a position in the string without consuming characters. They are powerful for matching patterns that need specific context, like finding numbers followed by a currency symbol or words not preceded by a specific prefix. These constructs are often confusing because they do not appear in the match itself. Use this tester to visualize exactly where your lookaheads and lookbehinds assert, and what the resulting match includes.