Regular Expressions 101

Sponsors

Community Patterns

2

Almost universal anime filename matcher

Created·2026-03-07 18:37
Flavor·Python
matches anime filenames. such as Group] Name [Episode[Audiometa]others.ext supports NCOP, NCED, OP, ED, SP, SPnn, nn, nn.n, nn.n_vn mp4, mkv, srt, ass but you could add more. the episode must be written within a [] bracket. finally, this regex cannot cover all the cases and obviously have some issues, but it's fine under most cases. it is also a small regex practice for me.
Submitted by NullCompute0754
2

Validate color with grb group

Created·2026-02-03 03:22
Updated·2026-02-04 03:36
Flavor·Golang
match: #aabbcc #abc (255,255,255) (255,255,255,255) 255,255,255 no match: #gggggg #ggg 256,256,256
Submitted by Doyoung
1

Door_Double

Created·2026-01-27 07:54
Updated·2026-01-28 10:27
Flavor·Python
Regex for Door_Double
Submitted by anonymous
1

ตรวจสอบพยัญชนะต้นตัวสะกดสระและวรรณยุกต์ไทย

Created·2026-01-22 01:36
Updated·2026-01-23 12:42
Flavor·ECMAScript (JavaScript)
ตรวจสอบพยัญชนะต้น (ต้องมี) ตรวจตัวสะกดสำหรับสระที่ต้องมี ตรวจสอบการวางสระและวรรณยุกต์ไทย หมายเหตุ การตรวจสอบตัวสะกดในภาษาไทยตรวจสอบได้ยากเพราะภาษาไทยเป็นภาษาที่เขียนติด ๆ กันไม่มีการแบ่งคำอย่างชัดเจนทำให้การอ่านภาษาไทยผู้อ่านต้องใช้ความหมายของคำในการตัดสินการอ่านแบ่งคำตามความเหมาะสมเช่นคำว่า "ตากลม" อาจอ่านเป็น "ตาก-ลม" ก็ได้ หรืออ่านเป็น "ตา-กลม"ก็ได้ ดังนั้นการเขียน Regex เพื่อทำการตรวจสอบอาจช่วยได้ระดับหนึ่ง อ่าจมีผิดบ้างถูกบ้าง แต่ก็ถือว่าเป็นเครื่องมือที่ใช้ช่วยเหลือในการตรวจสอบเพิ่มเติมได้ 80% ของความเป็นไปใด้ก็แล้วกันนะครับ หวังว่าการเขียนเพิ่มเติมส่วนนี้ จะมีประโยชน์บ้างไม่มากก็น้อย
Submitted by อธิปัตย์ ล้อวงศ์งาม
2

Secure Email Validation (OWASP-Aligned & DNS-Strict) (RFC 5322)

Created·2026-01-21 16:32
Updated·2026-01-21 16:36
Flavor·ECMAScript (JavaScript)
This regular expression provides a balance between RFC compliance and security-best-practices. It is designed to prevent injection vectors in legacy systems by using a restricted "safe" character subset recommended by the OWASP Validation Regex Repository. Pattern: ^A-Za-z0-9(?:\.A-Za-z0-9_+&-]+)*@(?:[A-Za-z0-9{0,61}[A-Za-z0-9])?\.)+[A-Za-z]{2,63}$ Key Features: Forced Alphanumeric Start: Prevents leading hyphens to avoid command injection vulnerabilities. Security Subset: Restricts special characters to _+&*- to prevent exotic character injections (e.g., pipes or backticks). No Quoted Strings: Forbids quoted strings to eliminate dangerous payloads containing spaces or backslashes. DNS Compliance: Enforces label lengths (1–63 characters) and prevents labels from starting or ending with hyphens. Whole String Anchoring: Uses ^ and $ to ensure the entire input is validated.
Submitted by Gor Sargsyan
1

Python -- Match container image reference parts

Created·2026-01-20 02:14
Updated·2026-01-20 02:28
Flavor·Python
This is a Python RE for matching different parts and combinations of various docker/container image references, as compatible with docker pull etc. Parts / Capture Groups image: # whole image repo: # everything but the tag/digest registry: # host+port host: port: name: # path within registry reference: # tag or digest (with : or @; I haven't bothered to figure out how to strip that yet) tag: digest: If it matches, it should match image, repo, and name at the very least.
Submitted by neal-ian
1

Check valid URI Scheme according to RFC2396

Created·2026-01-17 07:52
Flavor·Golang
Simple prefix matcher for validating URI Schemes according to [RFC2396, Section 3.1]( http://www.faqs.org/rfcs/rfc2396.html#3.5:~:text=well%20as%20%22http%22%29.-,scheme%20%20%20%20%20%20%20%20%3D%20alpha%20*%28%20alpha%20%7C%20digit%20%7C%20%22%2B%22%20%7C%20%22%2D%22%20%7C%20%22.%22%20%29,-Relative%20URI%20references) Go Playground: https://go.dev/play/p/vtYEugsNAfo
Submitted by Gwyneth Llewelyn
1

URL, URI format validation

Created·2026-01-16 16:16
Updated·2026-01-16 23:25
Flavor·ECMAScript (JavaScript)
URL, URI format validation
Submitted by Atipat Lorwongam
2

Regex Email Format

Created·2026-01-15 17:39
Updated·2026-01-16 23:26
Flavor·ECMAScript (JavaScript)
Used to check Email Format
Submitted by Atipat Lorwongam
1

ตรวจสอบวรรณยุกต์และสระในภาษาไทย (รองรับการลากเสียงอาาาา)

Created·2026-01-15 17:20
Updated·2026-01-23 07:30
Flavor·ECMAScript (JavaScript)
ตรวจสอบการใช้วรรณยุกต์และสระในภาษาไทย รองรับการใช้สระอาาาาาติดกันแบบลากเสียง ไม่ตรวจสอบพยัญชนะต้นและตัวสะกด
Submitted by อธิปัตย์ ล้อวงศ์งาม
1

ตรวจสอบวรรณยุกต์และสระในภาษาไทย

Created·2026-01-15 17:19
Updated·2026-01-23 07:29
Flavor·ECMAScript (JavaScript)
ใช้ตรวจสอบวรรณยุกต์และสระในภาษาไทย ไม่ตรวจสอบพยัญชนะต้นและตัวสะกด
Submitted by อธิปัตย์ ล้อวงศ์งาม
1

Simple CSS Selector parser

Created·2025-12-31 14:18
Updated·2025-12-31 14:22
Flavor·ECMAScript (JavaScript)
Basic Regex for CSS Selector. Pseudo-Elements, Combinators and other advanced stuff are not supported.
Submitted by anonymous
1

1

Created·2025-12-28 04:09
Flavor·Python
554
Submitted by anonymous
1

AoC 2025 Day 5

Created·2025-12-19 23:04
Flavor·Python
AoC 2025 Day 5 part 1 but also works for part 2. You just don't need the IDs at the bottom for part 2
Submitted by anonymous
1

Asw

Created·2025-12-17 05:38
Flavor·PCRE (Legacy)
``/^(?P0|1-9]\d)\.(?P0|[1-9]\d)\.(?P0|[1-9]\d)(?:-(?P(?:0|[1-9]\d|\d[a-zA-Z-)(?:\.(?:0|1-9]\d|\d[a-zA-Z-))))?(?:\+(?P[0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$/gmsAD
Submitted by anonymous
1

Text in between HTML tags and inside quotation marks within HTML tags

Created·2025-12-08 04:32
Flavor·ECMAScript (JavaScript)
Overview This Regular Expression shows any text between HTML tags or between quotation marks within the tags themselves. An example would be: <HTML lang="en", then selecting the 'en' from there. Group 1 is between tags, and group 2 is in the quotes. I recommend only using half of this regular expression, like the 'between tags' part, or the 'inside quotes part'. Explanation The whole regex is built of two alternates, the tags and quotes part. The tags part (the first part) starts with a lookbehind of a closing of a tag, then a lazy part that selects almost characters, and a lookahead that checks for the beginning of tag (so the text is between tags). The quotes part is built in a similar structure, where it looks behind for an open of a tag, .+ , then checking for an equals sign followed by a quotation mark. The middle section of the quotes part is again just searching for text, but also not including quotation marks. The lookahead checks for a closing quotation mark and that's it! Please comment any questions or email me.
Submitted by daniel@sabian.pro
1

Deucesanother

Created·2025-12-05 06:18
Flavor·PCRE (Legacy)
Fixwithpecra
Submitted by Deuces9ers
1

Regex for MusicBrainz Picard Plugin – Title Cleaner OST

Created·2025-11-28 16:26
Updated·2025-11-28 16:26
Flavor·Python
One of the regular expressions I use for my plugin Title Cleaner OST.
Submitted by nrth3rnlb
1

Posição Dianteira

Created·2025-11-21 16:15
Flavor·Python
Captura da posição dianteira e suas respectivas variações
Submitted by Erick Bryan Cubas
1

Universal HTML <input type="email"... requirement pattern

Created·2025-10-31 01:19
Flavor·ECMAScript (JavaScript)
This regex is a universal pattern used for the HTML input tag with type="email". Dont use type="email" as the pattern does not work with it. For the pattern to work correctly, use type="text" with inputmode="email" if you want to display the desired keyboard on mobile screens.
Submitted by kiko
1

IPv4 no leading zeros

Created·2025-10-28 09:57
Flavor·ECMAScript (JavaScript)
An IPv4 expression that doesn't allow leading zeros in octets. 10.0.0.1 will pass 10.0.0.01 shouldn't pass
Submitted by machfist
1

Cube Voyager Application Headers

Created·2025-10-24 05:43
Flavor·Python
Matching Cube Voyager Application Files
Submitted by On Dai Wai
1

dumb email

Created·2025-10-17 10:00
Flavor·Python
it is a naive email regex
Submitted by anonymous
1

Ultimate number selecter

Created·2025-10-07 02:25
Updated·2025-10-07 06:42
Flavor·Python
Selects all forms of numbers, ranging from decimals, to numbers with commas
Submitted by anonymous
1

Convetional commits

Created·2025-10-06 13:11
Flavor·Python
Convetional commits regex
Submitted by anonymous
1

Only one special character("-") per word

Created·2025-09-20 18:27
Flavor·ECMAScript (JavaScript)
Only one special character ("-") is allowed when entering a word
Submitted by anonymous
1

Email validation regex

Created·2025-09-05 11:27
Flavor·ECMAScript (JavaScript)
Compliant with RFC 5322
Submitted by valentinllpz
1

Integer Number

Created·2025-08-17 13:59
Updated·2025-08-17 14:06
Flavor·ECMAScript (JavaScript)
X
Submitted by Buddha
1

Replace last two digits of a four digit number with 99

Created·2025-08-14 17:59
Updated·2025-08-14 18:00
Flavor·Python
Replaces the last two digits of any four digit number with 99. Useful for replacing chart of account codes for accounting software mapping functionalities. Helpful for ProPay.
Submitted by Eric Higdon
1

URL matching

Created·2025-08-07 13:22
Flavor·Python
Matches URLs in texts. Forked from https://regex101.com/r/cX0pJ8/1 , then removed matching emails
Submitted by anonymous
1

email address

Created·2025-08-07 13:05
Flavor·Python
email address
Submitted by anonymous
1

op

Created·2025-07-29 00:21
Flavor·ECMAScript (JavaScript)
les
Submitted by anonymous
1

Detect age-related conversations.

Created·2025-07-21 08:50
Updated·2025-07-21 16:09
Flavor·ECMAScript (JavaScript)
Safety-measure protocol for online communities.
Submitted by mable42
1

Pixiv Profile ID Finder

Created·2025-07-18 19:27
Updated·2025-07-18 21:15
Flavor·Python
This is to find profile ids for pixiv.net
Submitted by secp192k1
1

Keep Talking and Nobody Explodes - Passwords

Created·2025-07-18 05:15
Flavor·Rust
See the chapter On the Subject of Passwords in Bomb Defusal Manual
Submitted by prprnya
1

regex for '' deletion

Created·2025-07-16 16:44
Updated·2025-07-16 16:44
Flavor·ECMAScript (JavaScript)
regex for '' deletion
Submitted by Egor K
1

Hex Color Validator

Created·2025-07-11 15:00
Flavor·Python
Verifies whether each input line contains a valid three- or six-digit hexadecimal number, commonly used as color codes in CSS and other technologies. Each number must begin with the "#" sign. I've seen other regexes for this which use individual expressions for a three-digit number and a six-digit number as alternates for each other. I didn't see any reason to repeat the character class twice, so I used only one pattern of three digits, which may appear one or two times. Valid Hex Color Codes #FFF #025 #F0A1FB Invalid Hex Color Codes #fffabg #abcf #12365erff
Submitted by Mr. Lance E Sloan
1

1

Created·2025-07-09 00:30
Updated·2025-07-09 00:33
Flavor·Golang
https://regex101.com/r/hIak43/1
Submitted by 1
1

Chess Algebraic Notation

Created·2025-07-07 19:15
Flavor·Python
Detects chess Algebraic notation. See: https://en.wikipedia.org/wiki/Algebraic_notation_(chess) Using Regexp groups to know what information is present on the notation (pieces or move disambiguation). Only supported by Flavor that has named group verification.
Submitted by Johan JANIN
1

Tag

Created·2025-07-04 07:14
Flavor·PCRE (Legacy)
Submitted by anonymous
1

RE-24806

Created·2025-07-03 11:56
Updated·2025-07-09 09:10
Flavor·Python
RE-24806
Submitted by anonymous
1

RE-24812

Created·2025-07-03 11:55
Updated·2025-07-09 07:56
Flavor·Python
RE-24812
Submitted by anonymous
1

RE-24799

Created·2025-07-03 09:36
Updated·2025-07-09 09:03
Flavor·Python
RE-24799
Submitted by anonymous
1

RE-24793

Created·2025-07-03 09:07
Updated·2025-07-09 07:34
Flavor·Python
RE-24793
Submitted by anonymous
1

RE-24781

Created·2025-07-03 05:26
Updated·2025-07-09 06:39
Flavor·Python
RE-24781
Submitted by anonymous
1

RE - 24755

Created·2025-06-25 08:48
Flavor·Python
RE - 24755
Submitted by anonymous
1

RE - 20475

Created·2025-06-25 07:55
Flavor·Python
RE - 20475
Submitted by anonymous
1

RE - 20473

Created·2025-06-25 07:45
Flavor·Python
RE - 20473
Submitted by anonymous
1

RE - 20485

Created·2025-06-24 06:29
Flavor·Python
RE - 20485
Submitted by anonymous
1

RE - 20482

Created·2025-06-24 06:25
Flavor·Python
RE - 20482
Submitted by anonymous

Community Library Entry

1

Regular Expression
Created·2025-07-07 19:15
Flavor·Python

r"
^(?:(?:(?P<piece>[prnbkq])?\s*(?P<from_col>[a-h])?(?P<from_row>[1-8])?\s*(?P<capture>x)?\s*(?P<to>[a-h][1-8]))|(?P<k_castling>(?P<char>[0O])\s*-\s*(?P=char))|(?P<q_castling>(?P<char2>[0O])\s*-\s*(?P=char2)\s*-\s*(?P=char2)))$
"
igm
Open regex in editor

Description

Detects chess Algebraic notation. See: https://en.wikipedia.org/wiki/Algebraic_notation_(chess)

Using Regexp groups to know what information is present on the notation (pieces or move disambiguation).

Only supported by Flavor that has named group verification.

Submitted by Johan JANIN