regex101: PCRE (Legacy) Match Workspace

^start of line

Group 1((?!-))

Negative Lookahead(?!-)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 2(xn--)?

?repeats the group contents below at most once:

xn--the literal text xn-- (case sensitive)

Character Class[a-z0-9]

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Character Class[a-z0-9-_]{0,61}

{0,61}matches between 0 and 61 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Character Class[a-z0-9]{0,}

{0,}matches any number of characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

\.?optionally matches the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 3((xn--)?([a-z0-9\-.]{1,61}|[a-z0-9-]{0,30})\.[a-z-1-9]{2,})

Group 4(xn--)?

?repeats the group contents below at most once:

xn--the literal text xn-- (case sensitive)

Group 5([a-z0-9\-.]{1,61}|[a-z0-9-]{0,30})

1st Alternative[a-z0-9\-.]{1,61}

Character Class[a-z0-9\-.]{1,61}

{1,61}matches between 1 and 61 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

.the literal . (46₁₀ / 56₈ / 2E₁₆)

2nd Alternative[a-z0-9-]{0,30}

Character Class[a-z0-9-]{0,30}

{0,30}matches between 0 and 30 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[a-z-1-9]{2,}

{2,}matches at least 2 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

1-9one character from 1 (49₁₀) to 9 (57₁₀)

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

^((?!-))(xn--)?[a-z0-9][a-z0-9-_]{0,61}[a-z0-9]{0,}\.?((xn--)?([a-z0-9\-.]{1,61}|[a-z0-9-]{0,30})\.[a-z-1-9]{2,})$

New

1c.ru
222.ru
g.com
111.222.22.2
2.eu
localhost
54.ru
ya.ru
www.pmmp.eiiil
129.0.0.100
127.0.0.1
22.22.22.220000
xn--b1aaa6i.xn--s1ak
sub.mkyong-info.com
mkyong.com.au
g.co
www.mk.mk.com
www.pl.bluemedia-testserver.ts.twisto.wtf
wwww.wwww.wwww.ww.w.wwww.www.ee
https://regex101.com/r/sP0rLU/1/
foodemo.net
bar.ba.test.co.uk
www.demo.com
http://foo.co.uk/
g.com
g-.com
com.g
-g.com
xn--d1ai6ai.xn--p1ai
xn--fsqu00a.xn--com
xn--stackoverflow.com
stackoverflow.xn--com
stackoverflow.co.uk
google.com.au
xn--b1aaaaaaaaaaaa96a.xn--b1aaaaaaaaaaaaa2vvc

-0-0o.com
a.net
0-0o.com
0-oz.co.uk
0-tension.com.br
0-wh-ao14-0.com-com.net
a-1234567890-1234567890-1234567890-1234567890-1234567890-1234-z.eu.us
a-1234567890-1234567890-1234567890-1234567890-1234567890-12345-z.eu.us (too long)

List of valid domain names:
www.google.com
google.com
mkyong123.com
mkyong-info.com
sub.mkyong.com
sub.mkyong-info.com
mkyong.com.au
g.co
mkyong.t.t.co

List of invalid domain:
mkyong.t.t.c
mkyong,com

Regular Expressions 101

Regular Expression

Extraction