Write a pattern?, paste test text, and see matches highlighted live. Capture groups? unpacked into a table. Replace mode included. All runs in your browser.
Regular expressions are a mini-language for describing text patterns — every email address, every phone number, every date in a document, whatever you can spell out. They power the “find” features in lots of tools, and they’re notoriously easy to get slightly wrong.
If a colleague, an article, or an AI handed you a pattern, paste it here along with a sample of real text and watch what lights up — so you know it catches the right things before you trust it. Nothing you paste leaves your machine.