Regex Generator

The ready-made patterns are practical rather than exhaustive: they accept the values people normally enter and reject typical mistakes. Every pattern is checked automatically against examples like these.

Rules describe what a valid value looks like without any regex syntax. For an invoice number such as INV-2024-0012: starts with INV-, allowed characters digits and -, length 8 to 14. For a PDF file name: ends with .pdf, allowed characters lower case, digits and -. Length counts the whole value, including the start and end text. “Contains” requires a piece of text anywhere in the value. Characters such as . or ( in your text are escaped automatically, so they match literally.

Type a few values, one per line. When they have the same shape — the same pieces of digits, letters and separators in the same order — the generator writes a pattern that captures that shape: INV-2024-0012 and INV-2025-0103 become ^INV\-\d{4}\-\d{4}$, which also accepts INV-2026-9999 but not INV-26-9999. When the examples differ in shape, it lists them as alternatives instead. Always check the result in the test box with values that should and shouldn't match.

Match the whole value adds ^ and $, which is what you want for validating a form field; turn it off, or choose Find all matches, to search inside longer text. The code snippets use each language's normal API: test() in JavaScript, re.search or findall in Python, preg_match in PHP and Pattern with find() in Java, with the case-insensitive flag when you choose it. Regex alone can't tell whether an email address exists or a date is real — combine it with proper checks where that matters. To experiment further, use the Regex Tester.