Validation

Email Address Validation

Validate that a whole string is an email address in the standard user@domain.tld format.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("^[a-zA-Z0-9._%+\\-]+@[a-zA-Z0-9.\\-]+\\.[a-zA-Z]{2,}$", "");
const input = "user@example.com";
const match = input.match(re);
console.log(match ? match[0] : null);

Uses `String.prototype.match`, which returns the first match or null.

Python (re) code

pyPython

import re

pattern = re.compile(r"^[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}$")
input_text = "user@example.com"
for m in pattern.finditer(input_text):
    print(m.group(0))

Stdlib `re` module — no third-party dependency. Works on Python 3.6+.

Go (RE2) code

goGo

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`^[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}$`)
	input := `user@example.com`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}

Uses `regexp.MustCompile` (panics on bad patterns at startup) and `FindAllString` for all matches.

Pattern

regexengine-agnostic

^[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}$

Raw source: ^[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}$

How it works

Anchored with ^ and $ so the entire input must be the address — without them, "contact: user@example.com" would pass. Matches a local part (letters, digits, dots, underscores, percent, plus, hyphen) followed by @, a domain name, a dot, and a TLD of at least 2 characters. To find emails inside longer text instead, drop the anchors and add the g flag.

Examples

Input

user@example.com

Matches

user@example.com

Input

hello.world+tag@sub.domain.org

Matches

hello.world+tag@sub.domain.org

Input

invalid-email

No match

—

Input

contact: user@example.com

No match

—

Common use cases

•Form input validation
•Validating email fields in API request payloads
•Filtering and de-duplicating contact lists

Related patterns

Email Domain Part (After @)

Validation

Validate just the domain portion of an email address — the bit after the @.

Email Local Part (Before @)

Validation

Validate just the local part of an email address (the bit before the @).

Cron Expression

Validation

Validate standard 5-field Unix cron expressions: minute, hour, day-of-month, month, day-of-week.

International Phone (E.164)

Validation

Validate phone numbers in ITU-T E.164 international format: a + sign followed by 2–15 digits, first digit non-zero.

Related concepts

Character Classes: \d, \w, \s and Their Negations

Concept

Shorthand character classes match broad categories of characters. \d is a digit, \w is a word character, \s is whitespace. Uppercase negates.

Quantifiers: *, +, ?, and {n,m}

Concept

Quantifiers repeat the preceding element. * is 0 or more, + is 1 or more, ? is 0 or 1. {n}, {n,}, and {n,m} give exact counts and ranges.

How to Validate an Email with Regex

How-to

Use a pragmatic regex for structural validation, then confirm deliverability separately. Full RFC 5322 compliance is overkill and error-prone.

All patterns

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