Regular Expressions 101

Sponsors

Community Patterns

1

Gooning67

Created·2026-04-29 07:12
Flavor·PCRE2 (PHP)
Gute KÄSE
Submitted by Goonlord69
1

3maldrehtsichderhaseimkreis

Created·2026-04-29 06:11
Flavor·PCRE2 (PHP)
wer den löwen weckt muss auch mit ihm tanzen
Submitted by anonymous
1

Halacae Text

Created·2026-04-01 00:09
Flavor·PCRE2 (PHP)
Regular expression to match a valid line of text in Halacae, a constructed language by R74n.
Submitted by R74n
1

Halacae Word

Created·2026-04-01 00:08
Flavor·PCRE2 (PHP)
Regular expression to match valid words in Halacae, a conlang by R74n.
Submitted by R74n
1

R74n URLs

Created·2026-04-01 00:05
Flavor·PCRE2 (PHP)
Regular expression to match valid URLs on R74n websites.
Submitted by R74n
1

TA_P1

Created·2026-03-26 09:45
Flavor·PCRE2 (PHP)
Code
Submitted by anonymous
1

plfjahr42

Created·2026-03-25 07:21
Flavor·PCRE2 (PHP)
plf HIIILLFFEEE
Submitted by Lecksie Hartman
1

plfJahr4

Created·2026-03-25 07:14
Flavor·PCRE2 (PHP)
PLF hiilfe
Submitted by Lecksie Hartman
1

Murat67

Created·2026-03-24 22:53
Flavor·PCRE2 (PHP)
Isch des Tüff
Submitted by webler4000
1

wald493#2

Created·2026-03-24 20:24
Flavor·PCRE2 (PHP)
Wer den Löwen weckt muss auch mit ihm tanzen!
Submitted by Webler3000
1

Capture group finder

Created·2026-03-23 19:06
Flavor·PCRE2 (PHP)
A regex to inspect other regex and match all capture groups
Submitted by SP4CEBAR
1

translation batch name structure

Created·2026-03-16 13:15
Flavor·PCRE2 (PHP)
internal structure of a batch name
Submitted by msoutopico
2

GHAS Custom Secret Scanning Regex for Password/Secret/API Key (Excludes ${...} and process.env)

Created·2026-03-06 15:52
Flavor·PCRE2 (PHP)
This is a GitHub Advanced Security (GHAS) Secret Scanning Custom Pattern I created to detect likely hardcoded credentials while reducing common false positives in code. Goal: detect assignments for these key names: password secret apikey / api_key / api-key Pattern regex: (?i)\b(password|secret|api[-]?key)\b\s[:=]\s(?!\s\$\{)(?!\sprocess\.env\b)(?:['"])?[A-Za-z0-9!@#$%^&()+=-]{5,}(?:['"])? What it should catch (examples): password: "ahsjdfahsjfhdjsahj" secret = 'kjfskahfsdhfj' apikey: ABCDE12345!@# (unquoted) What it tries NOT to catch (common false positives): password: ${password_somename} (template/variable placeholder) secret: ${VAULT_SECRET} password: process.env.DB_PASSWORD (env var reference, not a hardcoded secret) This is intended as a practical baseline; it won’t be perfect for every language/config style. If you have suggestions to improve the detection accuracy (reduce false positives/false negatives) for GHAS custom patterns, please share.
Submitted by GearoidMaguire
1

Flatten 1 line CSS

Created·2026-03-01 16:22
Updated·2026-03-01 17:35
Flavor·PCRE2 (PHP)
Finds CSS selectors that only contain one line and, using the substitution, flattens everything to be on the same line.
Submitted by anonymous
1

IP address

Created·2026-03-01 02:22
Flavor·PCRE2 (PHP)
Matches and verifies IP address. 192.168.0.1 Matches 999.999.9.9 Didn't match
Submitted by anonymous
1

Validate an IP

Created·2026-02-25 11:06
Updated·2026-02-25 11:11
Flavor·PCRE2 (PHP)
52 character long regex to validate IP address.
Submitted by Karthik
1

number selector, with commas & decimals

Created·2026-02-12 05:04
Flavor·PCRE2 (PHP)
selects numbers, with commas and decimals, like 1,234.56
Submitted by Bicorn
1

Smart outer parentheses selector with backslash escaping

Created·2026-02-10 03:26
Updated·2026-02-12 01:11
Flavor·PCRE2 (PHP)
Grabs the outer parentheses and contents taking into account inner parentheses enclosures
Submitted by bicorn
1

nexus/sonartype composer cleanup of unfinished package versions

Created·2026-02-05 13:05
Flavor·PCRE2 (PHP)
matches composer packages with -alpha, -beta and -rc versionings
Submitted by Anna Damm
1

OmegaT Project Name (Pattern)

Created·2026-02-03 16:49
Flavor·PCRE2 (PHP)
Regex showing how to match the five parts in an OmegaT project name (named as per the internal convention at cApStAn), including labels for each captured group (each part in the name).
Submitted by msoutopico
1

unnecessary closing HTML tags

Created·2026-01-27 19:15
Flavor·PCRE2 (PHP)
Selects the ` and ` tags from a string. You can probably do this with something easier, but this works
Submitted by Twineee
1

ตรวจสอบพยัญชนะต้นตัวสะกดสระและวรรณยุกต์ไทย

Created·2026-01-22 01:36
Updated·2026-01-23 12:42
Flavor·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·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

Laravel Log (MonoLog) Print

Created·2026-01-21 14:51
Updated·2026-01-21 15:00
Flavor·PCRE2 (PHP)
Extracts the following fields from a Laravel Log print: Time Stamp (Date) Log Level (supports optional prefix (ie. local.DEBUG)) Log Message Exception | Context If an exception is detected, the file reference (file path + line number), and optional stacktrace are captured.
Submitted by Jerren
1

Poland PESEL

Created·2026-01-21 11:23
Flavor·PCRE2 (PHP)
Correct Poland PESEL base regex validator. Covers birth dates up to 2099 year. PESEL numbers are in YYMMDDXXXXX format, however, the month is adjusted based on what year people were born. People born from 1900-1999 has no adjustment, 2000-2099 is the month +20, 2100-2199 is +40, 2200-2299 is +60. For example, if someone was born December 16, 2016, their PESEL would be 163216XXXXX.
Submitted by @Sldmk
1

PLF4 Formular mit Komponente

Created·2026-01-21 07:52
Flavor·PCRE2 (PHP)
PLF4
Submitted by anonymous
1

PLF3

Created·2026-01-21 07:38
Flavor·PCRE2 (PHP)
PLF3
Submitted by anonym
1

PLF2

Created·2026-01-21 07:22
Flavor·PCRE2 (PHP)
PLF2
Submitted by anonym
1

PLF1

Created·2026-01-21 07:20
Flavor·PCRE2 (PHP)
plf1
Submitted by anonym
1

Wasser

Created·2026-01-20 20:24
Flavor·PCRE2 (PHP)
hey das ist richtig coool oder?
Submitted by anonymous
1

URL, URI format validation

Created·2026-01-16 16:16
Updated·2026-01-16 23:25
Flavor·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·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·JavaScript
ตรวจสอบการใช้วรรณยุกต์และสระในภาษาไทย รองรับการใช้สระอาาาาาติดกันแบบลากเสียง ไม่ตรวจสอบพยัญชนะต้นและตัวสะกด
Submitted by อธิปัตย์ ล้อวงศ์งาม
1

ตรวจสอบวรรณยุกต์และสระในภาษาไทย

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

Match instagram URLs

Created·2026-01-13 23:29
Flavor·PCRE2 (PHP)
Matches instagram urls for posts, reels, and stories works on all flavors except rust
Submitted by User9684
1

Discord URL matching

Created·2026-01-13 23:19
Updated·2026-01-13 23:24
Flavor·PCRE2 (PHP)
match every type of discord url with each useful part in a group pretty optimized, shouldnt be too harsh on your system should work in every flavor except rust because rust sucks lol
Submitted by User9684
1

Match Bible References

Created·2026-01-12 14:12
Flavor·PCRE2 (PHP)
I've created this for a simple project of mine, it squishes every book of the Bible into a RegEx, with the full name, abbreviation, and abbreviation with a dot. Then, it matches the chapter and verse relatively simply.
Submitted by Twineee
1

Caculator seperator with groups

Created·2026-01-08 19:18
Flavor·PCRE2 (PHP)
Caculator seperator with groups
Submitted by CalcMan
1

Simple CSS Selector parser

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

HP Prime

Created·2025-12-30 04:20
Updated·2025-12-30 15:37
Flavor·PCRE2 (PHP)
Extracts HP Prime PPL numbers.
Submitted by anonymous
1

Strings

Created·2025-12-30 04:09
Updated·2025-12-30 04:11
Flavor·PCRE2 (PHP)
Extracting strings defined in languages like C/C++ etc.
Submitted by Insoft
1

U.S. Phone Number

Created·2025-12-23 19:40
Flavor·PCRE2 (PHP)
Format validation for U.S. phone numbers with or without a country code and with various formatting and punctuation permissible.
Submitted by Nick
1

Telephone validation regex - handles international codes, extensions, and formatting gracefully

Created·2025-12-19 21:17
Flavor·PCRE2 (PHP)
Search string for use in contact cleaning project $1 = intenational code, omitting preceding "+" $2 = area code $3 = first three digits of phone number $4 = last four digits of phone $5 = extension, inclusive of any commas or hashes to automate phone tree navigation TO DO handle recursive menus (e.g., "321-321-1234,,,1234#,,123344#....)
Submitted by Jason
1

Changes Log Tag verify for Languages Code sub-versioning

Created·2025-12-18 10:41
Flavor·PCRE2 (PHP)
Search for the occurence of the 3 following words: CHA, LOG and TAG. Should be in the above order sequence (but it also if works swapped).
Submitted by XrosaXasorX
1

DoubleQuote Enclosed CSV Field with Escaped DoubleQuote

Created·2025-12-11 12:04
Flavor·PCRE2 (PHP)
Extract field value of DoubleQuote Enclosed CSV Field with Escaped DoubleQuote The matching field value still contains escaped double quotes to be later processed :-)
Submitted by Alper YAZGAN
1

test

Created·2025-12-09 04:53
Flavor·PCRE2 (PHP)
test
Submitted by anonymous
1

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

Created·2025-12-08 04:32
Flavor·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

001

Created·2025-12-04 05:41
Flavor·PCRE2 (PHP)
for Problem 2 - Fancy Barcodes
Submitted by anonymous
1

souly2

Created·2025-11-26 11:03
Flavor·PCRE2 (PHP)
import React, { useState } from 'react'; // Example characters array as props for demonstration const charactersData = [ { name: 'Gandalf', isWizard: true }, { name: 'Harry', isWizard: true }, { name: 'Aragorn', isWizard: false } ]; // in der Component CharacterList function CharacterList({ characters }) { const [showOnlyWizards, setShowOnlyWizards] = useState(false); function handleFilterClick() { setShowOnlyWizards(!showOnlyWizards); } let visibleCharacters; if (showOnlyWizards) { visibleCharacters = characters.filter(function(character) { return character.isWizard === true; }); } else { visibleCharacters = characters; } return ( {showOnlyWizards ? 'Alle anzeigen' : 'Nur Zauberer anzeigen'} {visibleCharacters.map(function(character) { return {character.name}; })} ); } // in App.jsx export default function App() { return ; }
Submitted by anonymous
1

souly

Created·2025-11-26 10:52
Flavor·PCRE2 (PHP)
für julian <3
Submitted by anonymous

Community Library Entry

1

Regular Expression
Created·2023-01-02 01:10
Flavor·.NET 7.0 (C#)

@"
(?=^.{1,80}$)(^[^\p{C}<>+=;,*?\\\/\[\]\:\|""]+$)
"
gs
Open regex in editor

Description

There are specific requirements for the different components of a UNC path. While it's possible to try and validate the entire UNC path in one go, you quite often end up needing to break the path down anyway unless simply handing it off to some other library (in which case they should be providing validation for you!) and it's a lot simpler to validate the components individually.

Unfortunately, there can be quite a lot of flexibility with UNC paths, and Microsoft's Type Definition only goes so far, as it says that the format can depend on the protocol.

Thier type definition says that a share name must be 1-80 characters long, and the allowed characters are (hexidecimal ASCII/Unicode/UTF-8) x20-21, x23-29, x2B-2E, x30-39, x40-5A, x5E-7B, and x7D-FF. Careful observers may note that this actually includes some non-printable characters, notably x7F, the Delete code. I haven't had a chance to test whether you can actually create a share that includes it though.

My use case is UNC for SMB/CIFS, so I checked the SMB/CIFS protocol definitions and they refer back to the UNC definition, but also the Microsoft File System Control Codes definition for share names. Rather than listing what is allowed, it lists what is illegal, however they equate to exactly the same. It specifically says "All other Unicode characters are legal".

Therefore, I've taken an approach of firstly looking ahead to count the characters - you may want to remove this group from the RegEx if you check the length prior, and then checking the list of non-allowed characters, including all control codes. This may not be quite right according to the standards, however it is practical.

Submitted by thejamesdecker