Regex Generator

In short Describing what you want to match in plain English and getting a pattern back works well for the common shapes and needs checking for everything else — which is why examples matter more than the description. Supplying lines that should match, and ideally some that should not, turns a vague specification into a testable one, and it is the difference between a pattern that looks right and one that is. Two warnings that apply to any generated regex. First, test the negative cases: a pattern that matches everything you wanted is only half correct if it also matches things you did not, and that half is invisible until it causes a problem. Second, be careful with the classic "validate an email" and "validate a URL" requests. The fully correct patterns are enormous and the short ones are all subtly wrong, which is why the practical advice is to use a permissive pattern and verify by sending a message rather than a strict one that rejects valid addresses. And always anchor a validation pattern, or it will match a valid fragment inside invalid input.