Regex tester

It walks every element of the pattern: character classes, ranges, quantifiers, anchors, word boundaries, lookahead/lookbehind, backreferences, and the effect of each enabled flag. It also reports how many capture groups the pattern declares.

Lookarounds do not consume input, so a pattern of only lookarounds matches an empty string at a position. See them reflected in the explanation section so you can confirm the surrounding characters are also matched.

No. The pattern is compiled and executed in your browser with native keyword RegExp, and parsing for the explanation is done locally. Nothing leaves the page.

The global flag scans the whole string for all matches. The sticky flag anchors matching to the position held by lastIndex, so it only matches if the pattern occurs beginning exactly at that position. This tester shows both behaviors live.

Yes. Patterns that reference an earlier group with \1 work in the live matcher, and the capture group table fills with the values each group captured as you adjust the test text.

A regex tester is an interactive tool where you paste a pattern and a test string and instantly see every match, its position, and its capture groups. This one adds a plain-English explanation, turning the tester into a learning environment for regular expressions.

Paste your pattern into the pattern field and your test text into the test field. Every match highlights live, the match positions and capture-group values update, and the flags can be toggled to see how each affects the result.

Regex is used for searching, validating, and transforming text: checking emails or phone numbers, extracting fields from logs, finding patterns in documents, and replacing text in code or editors. It is the universal syntax for text matching.

A regex check is a quick validation that runs a pattern against your text to confirm it matches - like verifying an email format or a date string. This tester performs the check instantly and highlights every location that satisfies the pattern.

Regex is not a general-purpose programming language, but it is a formal language used inside many languages and tools. It describes patterns with its own concise syntax, so it is often called a domain-specific language for text matching.

Start with the fundamentals - literal characters, character classes, quantifiers, anchors, and groups - and practice against real text. This page explains each pattern in plain English and shows matches live, which shortens the learning curve significantly.

Yes. Regex is a practical tool in AI pipelines for cleaning and validating text, extracting structured fields from model output, and parsing data before models process it. Learning regex complements AI tools rather than replacing them.

Google's search engine does not use regex, but many Google products do - Google Sheets, BigQuery, and Google Ads support regex in filters, queries, and targeting. This tester is useful for verifying any of those patterns before deploying them.

Regex syntax is built from characters, meta-characters like . * + ? and { }, anchors like ^ and $, character classes in [], groups in (), and flags. The plain-English explanation on this page reads your pattern back so you can write it correctly the first time.