Regex.ai

A single run produces four patterns, each generated by an agent with a different strategy. Agent A generalizes the way a person would, reaching for a rule that covers the spirit of your highlights. Agent B looks for a pattern shared by the highlighted strings and the text around them. Agent C targets adjacent single characters. Agent D concentrates on the count and type of characters. Having four answers side by side is the point: you see how the pattern behaves on the parts of your text you never highlighted, and you pick the one that doesn't overreach.

The interface works like selecting text in a document. You drag over a value, it lights up, and the tool treats it as an example of what to capture. Select several and click Run. Mistakes cost nothing: a click on any highlight removes it, and you can keep adjusting until the examples cover every variant in the text. There's no prompt to write and no syntax to recall, which is what separates this from pasting into a general-purpose chatbot.

Each agent's result is tested against your complete input, not just the strings you marked. You see which parts of the document the pattern captures and, more usefully, what it picks up by accident. That view is what breaks a tie between two plausible answers. A pattern that matches your three examples and nothing else looks different from one that sweeps up a dozen unrelated values, and the preview makes the difference obvious before you copy a single character.

The documentation page doubles as a syntax guide. It covers the metacharacters that do the heavy lifting, including brackets, anchors, quantifiers, alternation, and grouping, plus the special sequences for digits, word boundaries, and whitespace. Each entry comes with a short example. For anyone learning the language, having the reference one click from the working tool saves a round trip to a separate cheat sheet. It's a basic reference, not a tutorial series.

Everything runs in the browser and nothing is gated. There's no sign-up form, no paid tier, and no feature that unlocks after purchase. The service is licensed for personal, non-commercial use, so commercial teams should read the terms before relying on it in production work. For individual developers and students, the lack of friction is the main draw: open the tab, solve the problem, close the tab.

The about page advertises a companion tool builder that's meant to sit alongside the generator, aimed at people who want to wrap an extraction task into a repeatable setup. The link currently returns a 404, so it's not usable today. Treat this as a roadmap item rather than a feature you can count on when planning work.