Regex Explainer

About this tool

Paste a regular expression and get a plain-English, token-by-token explanation of what each part matches.

Example

Input: ^\d{3}-\d{4}\$

Output: ^ → start, \d → digit, {3} → 3 times...

Privacy

This tool runs entirely in your browser. Your data is processed locally and never uploaded to a server.

How to use this tool

1. Paste your regular expression into the input box.
2. Read the token-by-token explanation to see what each symbol means.
3. Use the example area to compare the pattern with a real sample string.
4. Adjust the regex and recheck the explanation until it matches your intent.

Step by step, what happens

1. The tool reads the regex from left to right and splits it into tokens or small pattern parts.
2. It identifies common constructs such as literal characters, character classes, groups, quantifiers, anchors, and escapes.
3. Each token is rewritten in plain English so you can understand what it matches without decoding regex syntax yourself.
4. The tool presents the explanation alongside the original pattern, making it easier to spot mistakes like overmatching or missing escapes.

Worked example

If you want to understand a common email-like pattern, try a simple regex that matches a word, an at sign, and another word.

Input: ^\w+@\w+\.com$

1. Paste the pattern into Regex Explainer.
2. The tool explains that ^ means the match must start at the beginning, \w+ means one or more word characters, and @ matches a literal at sign.
3. It then explains the rest of the pattern, including the escaped dot before com and the $ end anchor.
4. You can compare that explanation with your intended input, such as test@example.com.

Tips and common mistakes

• Remember that backslashes matter, so \d, \w, and \. mean very different things from plain d, w, and .
• If the explanation looks broader than you expected, check for greedy quantifiers like * and + that may match more than one part.
• Anchors like ^ and $ change whether the pattern must match the whole string or just part of it.
• Character classes like [abc] and [^abc] are easy to misread, so verify whether the explanation says include or exclude.

Frequently asked questions