RegEx Validation: Cheatsheet of the most common regular expressions for validation (+ HowTo)

Regular expressions are often used to validate user input. These are repeated when validating the same input. Therefore I have created a list with the most important RegEx strings.

Just save this article and copy the corresponding regular expression into your next project where you need it.

For all RegEx validations there are infinite possibilities in the implementation. I have tested all the ones shown here extensively.

To test regular expressions more easily and not run into trial and error there are several tools online. I have linked my favorite RegEx Validator here:

RegEx Validator

Validate date & time

Date in the format YYYMMDD (0-9999 years)

(?<!\d)(?:(?:(?:1[6-9]|[2-9]\d)?\d{2})(?:(?:(?:0[13578]|1[02])31)|(?:(?:0[1,3-9]|1[0-2])(?:29|30)))|(?:(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00)))0229)|(?:(?:1[6-9]|[2-9]\d)?\d{2})(?:(?:0?[1-9])|(?:1[0-2]))(?:0?[1-9]|1\d|2[0-8]))(?!\d)

Date in the format YYYY-MM-DD

^\d{4}\-(0?[1-9]|1[012])\-(0?[1-9]|[12][0-9]|3[01])$

Date in the format DD.MM.YYYY (without leading zeros)

^[0-3]?[0-9][\/.][0-3]?[0-9][\/.](?:[0-9]{2})?[0-9]{2}$

Date in the format DD.MM.YYYY (with leading zeros)

^[0-3][0-9][\/.][0-3][0-9][\/.](?:[0-9][0-9])?[0-9][0-9]$

Date in M/D/YYY format

^(0?[1-9]|[12][0-9]|3[01])[\/\-](0?[1-9]|1[012])[\/\-]\d{4}$

Time in HH:MM format (24 hours format)

^([0-1]?[0-9]|2[0-3]):[0-5][0-9]$

Time in HH:MM:SS format (24 hours format)

^([0-1]?[0-9]|2[0-3]):[0-5][0-9]:[0-5][0-9]$

Time in HH:MM format (12 hours format)

^(0?[1-9]|1[0-2]):[0-5][0-9]$

Time in HH:MM:SS format (12 hours format)

^(0?[1-9]|1[0-2]):[0-5][0-9]:[0-5][0-9]$

Time in H:MM AM/PM format

^((1[0-2]|0?[1-9]):([0-5][0-9]) ?([AaPp][Mm]))$

Time in the format H:MM:SS AM/PM

^((1[0-2]|0?[1-9]):([0-5][0-9]):([0-5][0-9]) ?([AaPp][Mm]))$

Validate password

Only numbers and letters (at least 8 characters)

^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)[a-zA-Z\d]{8,}$

Numbers, upper and lower case letters (at least 12 characters)

^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&#\^]{12,}$

Validate phone numbers & mobile numbers

Recognizes most popular formats (different countries)

(\(?([\d \-\)\–\+\/\(]+)\)?([ .\-–\/]?)([\d]+))

Validate email address

Only email addresses from specific domains (here *@gmail.com and @hotmail.com)

^([\w\-\.]+@(?!gmail.com)(?!hotmail.com)([\w\- ]+\.)+[\w-]{2,4})?$

For all domains

^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$

Validate URL

Only URLs with FTP protocol

^(ftp:\/\/)[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?(\/.*)?$

Standard URLs (only in the following format: http(s)://example.com/ , including ports)

^(http:\/\/|https:\/\/)[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?(\/.*)?$

All possible URL formats (including IP addresses and anchors)

^(?:http(s)?:\/\/)?[\w.-]+(?:\.[\w\.-]+)+[\w\-\._~:/?#[\]@!\$&'\(\)\*\+,;=.]+$

Implementation in different programming languages

Validation in different programming languages always looks slightly different. However, in general it is identical.

In all examples you just replace the variable regex with one of the above and the stringToValidate should contain a string with the respective user input.

RegEx Validierung in JavaScript

let stringToValidate = "ZH*EnD?vv9Xf&y8"; // e.g. value from a textarea
let regex =
  /^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&#\^]{12,}$/; // attention: no quotes!

if (stringToValidate.match(regex)) {
  // valid input
} else {
  // invalid input
}

RegEx Validierung in PHP

$stringToValidate = "ZH*EnD?vv9Xf&y8";
$regex = "/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&#\^]{12,}$/"; // attention: add a slash at the begin and the end

if (preg_match($regex, $stringToValidate)) {
	// valid input
} else {
	// invalid input
}

RegEx Validierung in Java

String stringToValidate = "ZH*EnD?vv9Xf$y8";
String regex = "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[@$!%*?&])[A-Za-z\\d@$!%*?&#\\^]{12,}$";

if (stringToValidate.matches(regex)) {
	// valid input
} else {
	// invalid input
}

What validation is still missing here? Feel free to write me a comment! 🙂