Regex Pattern Library
201 tested regex patterns for email, phone, URL, password, UUID, date, credit card, and more. Each page has copy-paste code for JavaScript, Python, Ruby, PHP, and Java.
Quick Answer
Regex (regular expressions) define patterns for matching text. Common uses: validating email, phone numbers, URLs, passwords; extracting data; find-and-replace. Most languages use PCRE-compatible syntax with minor differences in flags and escaping. Click any pattern below for tested examples and copy-paste code in 5 languages.
Common Validation
Email Address
Validates a standard email address format
^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA...Email (RFC 5322 Compliant)
RFC 5322 compliant email validation with label length limits
^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-...URL (HTTP/HTTPS)
Validates HTTP and HTTPS URLs
^https?:\/\/(?:[\w-]+\.)+[a-zA-Z]{2,}(?:...URL (Any Protocol)
Matches URLs with any protocol (http, https, ftp, ws, etc.)
^(?:[a-zA-Z][a-zA-Z0-9+.-]*:\/\/)[^\s/$....Domain Name
Validates a domain name (no protocol)
^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-z...Email Username Part
Extracts the local/username part of an email address
^([a-zA-Z0-9._%+-]+)@Email Domain Part
Extracts the domain part of an email address
@([a-zA-Z0-9.-]+\.[a-zA-Z]{2,})$Email with Plus Addressing
Email address using plus/sub-addressing (user+tag@domain.com)
^[a-zA-Z0-9._%+-]+\+[a-zA-Z0-9._%+-]+@[a...Email with Subdomain
Email address with a subdomain in the domain part
^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9-]+\.[a-zA-...Phone Numbers
US Phone Number
US phone number in common formats
^\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?(...International Phone (E.164)
Validates E.164 international format — + followed by 2-15 digits
^\+[1-9]\d{1,14}$Indian Phone Number
Indian mobile number with optional +91 country code
^(?:\+91[- ]?)?[6-9]\d{9}$UK Phone Number
UK mobile number with optional +44 country code
^(?:\+44|0)7\d{9}$French Phone Number
French phone number with optional +33 country code
^(?:\+33|0)[1-9](?:[\s.-]?\d{2}){4}$German Phone Number
German phone number with optional +49 country code
^(?:\+49|0)[1-9]\d{1,14}$Japanese Phone Number
Japanese phone number with optional +81 country code
^(?:\+81|0)\d{1,4}[- ]?\d{1,4}[- ]?\d{4}...Australian Phone Number
Australian mobile number with optional +61 country code
^(?:\+61|0)4\d{8}$Brazilian Phone Number
Brazilian phone number with optional +55 country code
^(?:\+55)?\d{2}9?\d{8}$Passwords
Strong Password
At least 8 chars with uppercase, lowercase, digit, and special character
^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!...Password 12+ Characters
At least 12 characters with uppercase, lowercase, and digit
^(?=.*[a-z])(?=.*[A-Z])(?=.*\d).{12,}$Strong Password (12+ chars)
Strong password: 12+ characters with uppercase, lowercase, digit, and special character
^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[!@#...4-Digit PIN
Four-digit PIN code
^\d{4}$6-Digit PIN
Six-digit PIN code
^\d{6}$6-Digit OTP Code
Six-digit one-time password (OTP)
^\d{6}$Networking
IPv4 Address
Validates a well-formed IPv4 address (0-255 in each octet)
^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)...IPv6 Address
Basic IPv6 address (8 groups of 4 hex digits)
^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$MAC Address
MAC address with colons or dashes as separators
^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})...IPv4 CIDR Notation
IPv4 address with CIDR subnet mask (e.g. 10.0.0.0/24)
^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)...Private IP Address
RFC 1918 private IPv4 address ranges (10.x, 172.16-31.x, 192.168.x)
^(10\.\d{1,3}\.\d{1,3}\.\d{1,3}|172\.(1[...Localhost Detection
Detects localhost URLs (localhost, 127.0.0.1, ::1)
^(?:https?:\/\/)?(?:localhost|127\.0\.0\...CIDR Notation (Generic)
Generic CIDR notation for IPv4 or IPv6 with subnet mask
^[0-9a-fA-F:.]+\/\d{1,3}$IPv4 Address with Port
IPv4 address followed by colon and port number
^((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)...Payment
Visa Credit Card
Visa card — starts with 4, 13 or 16 digits total
^4[0-9]{12}(?:[0-9]{3})?$Mastercard Credit Card
Mastercard — 16 digits starting with 51-55 or 2221-2720
^(?:5[1-5][0-9]{14}|2(?:2(?:2[1-9]|[3-9]...American Express Card
Amex — 15 digits starting with 34 or 37
^3[47][0-9]{13}$Any Credit Card
Visa, Mastercard, Amex, Discover, Diners
^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{...Discover Credit Card
Discover card — starts with 6011 or 65, 16 digits total
^6(?:011|5[0-9]{2})[0-9]{12}$Diners Club Credit Card
Diners Club card — starts with 300-305, 36, or 38, 14 digits total
^3(?:0[0-5]|[68][0-9])[0-9]{11}$JCB Credit Card
JCB card — starts with 3528-3589, 16 digits total
^35(?:2[89]|[3-8][0-9])[0-9]{12}$IBAN Number
International Bank Account Number (IBAN) format
^[A-Z]{2}\d{2}[A-Z0-9]{4}\d{7}(?:[A-Z0-9...SWIFT/BIC Code
SWIFT/BIC bank identifier code (8 or 11 characters)
^[A-Z]{4}[A-Z]{2}[A-Z0-9]{2}(?:[A-Z0-9]{...US Routing Number
US bank routing number (ABA) — exactly 9 digits
^\d{9}$UK Sort Code
UK bank sort code (6 digits, optional dashes)
^\d{2}-?\d{2}-?\d{2}$Currency Amount (Generic)
Currency amount with ISO 4217 code (e.g. USD 1,234.56)
^[A-Z]{3}\s?\d{1,3}(?:[,.]\d{3})*(?:[,.]...Bitcoin Address
Bitcoin address (Legacy P2PKH, P2SH, or Bech32)
^(?:bc1|[13])[a-zA-HJ-NP-Z0-9]{25,39}$Ethereum Address
Ethereum address — 0x prefix followed by 40 hex characters
^0x[0-9a-fA-F]{40}$UnionPay Credit Card
UnionPay card — starts with 62, 16-19 digits total
^62[0-9]{14,17}$Identifiers
UUID v4
UUID version 4 (randomly generated)
^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[8...UUID (Any Version)
Any RFC 4122 UUID (versions 1-5)
^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3...JWT Token
JSON Web Token (header.payload.signature)
^[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+\.[A-Za-z...Hex String
Any-length hexadecimal string
^[0-9a-fA-F]+$Base64 String
Standard base64 encoded string
^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2...Alphanumeric Username
Username with letters, digits, underscores (3-16 chars)
^[a-zA-Z0-9_]{3,16}$Twitter Handle
Twitter/X handle, 1-15 chars, optional @
^@?(\w){1,15}$URL Slug
Lowercase URL-friendly slug with dashes
^[a-z0-9]+(?:-[a-z0-9]+)*$US Social Security Number
US SSN format (XXX-XX-XXXX) with basic validity checks
^(?!000|666|9\d{2})\d{3}-(?!00)\d{2}-(?!...US EIN (Employer ID)
US Employer Identification Number (XX-XXXXXXX)
^\d{2}-\d{7}$EU VAT Number
EU VAT identification number (country code + digits)
^[A-Z]{2}\d{2,12}$Indian PAN Number
Indian Permanent Account Number (AAAAA1234A)
^[A-Z]{5}\d{4}[A-Z]$Git Commit Hash
Git commit SHA hash (7-40 hex characters)
^[0-9a-f]{7,40}$Git Branch Name
Valid git branch name following git-check-ref-format rules
^(?!.*\.\.)(?!.*\/\/)(?!\/)[a-zA-Z0-9/_....Strict URL Slug
Strict slug: starts with letter, lowercase alphanumeric with dashes
^[a-z][a-z0-9]*(?:-[a-z0-9]+)*$Social Handle (@)
Social media handle with @ prefix (1-30 chars)
^@[a-zA-Z0-9_]{1,30}$AWS ARN
Amazon Web Services ARN (Amazon Resource Name)
^arn:aws[a-zA-Z-]*:[a-zA-Z0-9-]+:[a-z]{2...AWS S3 Bucket Name
Valid AWS S3 bucket name (3-63 chars, lowercase)
^[a-z0-9][a-z0-9.-]{1,61}[a-z0-9]$AWS Region
AWS region identifier (e.g. us-east-1)
^[a-z]{2}-[a-z]+-\d$AWS Account ID
AWS account ID — exactly 12 digits
^\d{12}$Google Analytics ID
Google Analytics tracking ID (UA or GA4)
^(?:UA-\d{4,10}-\d{1,4}|G-[A-Z0-9]{10,})...Google Tag Manager ID
Google Tag Manager container ID
^GTM-[A-Z0-9]{6,8}$Stripe API Key
Stripe publishable, secret, or restricted key format
^(?:pk|sk|rk)_(?:test|live)_[a-zA-Z0-9]{...ISBN-10
ISBN-10 — 9 digits plus a check digit (0-9 or X)
^\d{9}[\dX]$ISBN-13
ISBN-13 — starts with 978 or 979, 13 digits total
^97[89]\d{10}$DOI Number
Digital Object Identifier (DOI) starting with 10.
^10\.\d{4,9}\/[-._;()/:a-zA-Z0-9]+$VIN (Vehicle ID)
Vehicle Identification Number — 17 alphanumeric chars (no I, O, Q)
^[A-HJ-NPR-Z0-9]{17}$TOTP Secret (Base32)
Base32-encoded TOTP secret key (16+ uppercase letters and 2-7)
^[A-Z2-7]{16,}$JWT Token (Strict)
Strict JWT starting with eyJ (base64 encoded JSON header and payload)
^eyJ[A-Za-z0-9-_]+\.eyJ[A-Za-z0-9-_]+\.[...Bearer Auth Header
HTTP Bearer Authorization header value
^Bearer\s+[A-Za-z0-9._~+/=-]+$Basic Auth Header
HTTP Basic Authorization header (base64 encoded credentials)
^Basic\s+[A-Za-z0-9+/]+=*$Base64 String (Strict)
Strict base64 encoded string (min 4 chars, proper padding)
^[A-Za-z0-9+/]{4,}(?:={0,2})$CVE Identifier
Common Vulnerabilities and Exposures (CVE) ID
^CVE-\d{4}-\d{4,}$Generic API Key
Generic API key format (20+ alphanumeric, underscore, or dash characters)
^[a-zA-Z0-9_-]{20,}$US License Plate
US license plate — 1-8 uppercase alphanumeric characters
^[A-Z0-9]{1,8}$Slack Channel Name
Valid Slack channel name (lowercase, max 80 chars)
^[a-z0-9][a-z0-9_-]{0,79}$Discord Username
Discord username (2-32 chars, lowercase alphanumeric with dots and underscores)
^[a-z0-9_.]{2,32}$Date & Time
Date YYYY-MM-DD
ISO 8601 date format
^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[...Date DD/MM/YYYY
European date format with slashes
^(0[1-9]|[12]\d|3[01])\/(0[1-9]|1[0-2])\...24-Hour Time
24-hour clock time in HH:MM format
^([01]\d|2[0-3]):([0-5]\d)$12-Hour Time with AM/PM
12-hour clock with AM/PM
^(0?[1-9]|1[0-2]):([0-5]\d)\s?(AM|PM|am|...Date MM/DD/YYYY
US date format with slashes (MM/DD/YYYY)
^(0[1-9]|1[0-2])\/(0[1-9]|[12]\d|3[01])\...ISO 8601 Full DateTime
Full ISO 8601 datetime with timezone (YYYY-MM-DDThh:mm:ssZ)
^\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\...Time with Milliseconds
Time in HH:MM:SS.mmm format with milliseconds
^([01]\d|2[0-3]):([0-5]\d):([0-5]\d)\.\d...Time AM/PM Format
12-hour time with optional seconds and AM/PM
^(0?[1-9]|1[0-2]):([0-5]\d)(?::([0-5]\d)...Unix Timestamp
Unix timestamp in seconds (10 digits) with optional microseconds
^\d{10}(?:\.\d{1,6})?$ISO 8601 Duration
ISO 8601 duration format (e.g. P1Y2M3DT4H5M6S)
^P(?!$)(?:\d+Y)?(?:\d+M)?(?:\d+W)?(?:\d+...Year (4-digit)
Four-digit year between 1900 and 2099
^(?:19|20)\d{2}$Month Name
Full English month name
^(?:January|February|March|April|May|Jun...Postal Codes
US ZIP Code
5-digit ZIP or ZIP+4 format
^\d{5}(?:-\d{4})?$UK Postcode
UK postcode format
^[A-Z]{1,2}\d[A-Z\d]? ?\d[A-Z]{2}$Indian PIN Code
6-digit Indian PIN code
^[1-9][0-9]{5}$Canadian Postal Code
Canadian postal code (letter-digit-letter digit-letter-digit)
^[A-Z]\d[A-Z] ?\d[A-Z]\d$German Postal Code
German postal code — exactly 5 digits
^\d{5}$Japanese Postal Code
Japanese postal code (XXX-XXXX)
^\d{3}-\d{4}$French Postal Code
French postal code — exactly 5 digits
^\d{5}$Numbers
Positive Integer
Integers greater than zero (no leading zeros)
^[1-9]\d*$Non-negative Integer
Zero or positive integer
^(0|[1-9]\d*)$Decimal Number
Optionally signed decimal number
^-?\d+(?:\.\d+)?$Hex Color Code
3 or 6-digit hex color with optional #
^#?([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$USD Currency
US dollar amount with optional $ and thousands separators
^\$?\d{1,3}(,\d{3})*(\.\d{2})?$Hex Color with Alpha
Hex color code with optional alpha channel (3, 4, 6, or 8 digits)
^#?([A-Fa-f0-9]{8}|[A-Fa-f0-9]{6}|[A-Fa-...RGB Color
CSS RGB color function rgb(r, g, b)
^rgb\(\s*(\d{1,3})\s*,\s*(\d{1,3})\s*,\s...HSL Color
CSS HSL color function hsl(h, s%, l%)
^hsl\(\s*\d{1,3}\s*,\s*\d{1,3}%\s*,\s*\d...Scientific Notation
Number in scientific notation (e.g. 1.5e10)
^-?\d+(?:\.\d+)?[eE][+-]?\d+$Percentage Value
Numeric percentage with % sign
^-?\d+(?:\.\d+)?%$Latitude/Longitude
Geographic coordinates (lat, lng) — lat -90 to 90, lng -180 to 180
^-?(?:[1-8]?\d(?:\.\d+)?|90(?:\.0+)?),\s...CSS Named Color
Common CSS named colors
^(?:red|blue|green|black|white|gray|grey...File Paths
File Extension
File extension at the end of a filename
\.[a-zA-Z0-9]+$Image File Extension
Common image file extensions
\.(jpg|jpeg|png|gif|bmp|webp|svg|avif|he...Video File Extension
Common video file extensions
\.(mp4|mov|avi|mkv|webm|flv|wmv|m4v)$Absolute Unix Path
Absolute filesystem path starting with /
^\/(?:[^\/\0]+\/)*[^\/\0]*$Windows File Path
Windows absolute file path (C:\folder\file.txt)
^[a-zA-Z]:\\(?:[^\\/:*?"<>|\r\n]+\\)*[^\...Unix File Path
Unix absolute file path (must have at least one path component)
^\/(?:[^\/\0]+\/)*[^\/\0]+$Filename with Extension
Filename with at least one extension
^[a-zA-Z0-9][a-zA-Z0-9._-]*\.[a-zA-Z0-9]...Filename without Extension
Filename with no dots or extension
^[a-zA-Z0-9][a-zA-Z0-9_-]*$Audio File Extension
Common audio file extensions
\.(mp3|wav|flac|aac|ogg|wma|m4a|opus)$Document File Extension
Common document file extensions
\.(pdf|doc|docx|xls|xlsx|ppt|pptx|txt|cs...S3 Object Key
Valid AWS S3 object key (safe characters)
^[a-zA-Z0-9!_.*'()-][a-zA-Z0-9!_.*'()/ -...HTML & Markup
HTML Tag
Any HTML tag (opening, closing, or self-closing)
<\/?[a-zA-Z][a-zA-Z0-9]*(?:\s+[^>]*)?\/?...HTML Comment
HTML comment block (multi-line safe)
<!--[\s\S]*?-->HTML Attribute
HTML attribute key-value pair (attr="value")
([a-zA-Z][a-zA-Z0-9-]*)\s*=\s*["']([^"']...HTML Self-Closing Tag
Self-closing HTML tags like <br/>, <img/>, <input/>
<([a-zA-Z][a-zA-Z0-9]*)(?:\s+[^>]*)?\/?>HTML Entity
HTML character entity (named or numeric)
&(?:#[0-9]+|#x[0-9a-fA-F]+|[a-zA-Z]+);Semantic HTML5 Tag
HTML5 semantic element tags
<\/?(article|aside|details|figcaption|fi...XML Namespace
XML namespace declaration (xmlns or xmlns:prefix)
xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\s*=\s*"[...Whitespace
Web & Network
Subdomain Extraction
Extracts the subdomain from a URL or domain name
^(?:https?:\/\/)?([a-zA-Z0-9](?:[a-zA-Z0...Protocol Detection
Detects and captures the protocol from a URL
^([a-zA-Z][a-zA-Z0-9+.-]*):\/\/Port Number
Extracts port number from a URL or host string
:([0-9]{1,5})(?:\/|$)Query Parameter
Extracts key-value pairs from URL query strings
[?&]([a-zA-Z0-9_]+)=([^&#]*)HTTP vs HTTPS URL
Matches HTTP or HTTPS URLs and captures the protocol
^(https?):\/\/[^\s]+$Data URL
Matches data: URL scheme with optional MIME type and base64 encoding
^data:([a-zA-Z]+\/[a-zA-Z0-9.+-]+)?(;bas...WebSocket URL
WebSocket URL starting with ws:// or wss://
^wss?:\/\/[^\s/$.?#].[^\s]*$FTP URL
FTP or FTPS URL
^ftps?:\/\/[^\s/$.?#].[^\s]*$SSH URL
SSH connection string (ssh:// or user@host format)
^(?:ssh:\/\/)?(?:[a-zA-Z0-9._-]+@)?[a-zA...Git URL
Git repository URL (HTTPS, SSH, or git:// protocol)
^(?:git|https?|ssh):\/\/[^\s]+\.git$|^[a...MIME Type
Standard MIME type format (type/subtype)
^[a-zA-Z]+\/[a-zA-Z0-9.+-]+$Content-Type Header
HTTP Content-Type header with optional parameters
^[a-zA-Z]+\/[a-zA-Z0-9.+-]+(?:\s*;\s*[a-...Browser User Agent
Detects browser-style User-Agent strings starting with Mozilla/5.0
Mozilla\/5\.0\s+\([^)]+\)Bot User Agent
Detects common bot/crawler User-Agent keywords
(?:bot|crawl|spider|slurp|fetch|archiv)(...GitHub Repository URL
GitHub repository URL
^https:\/\/github\.com\/[a-zA-Z0-9._-]+\...X-Forwarded-For Header
X-Forwarded-For header with comma-separated IPs
^(?:\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}(?...CORS Origin
CORS Access-Control-Allow-Origin value (* or origin URL)
^(?:\*|https?:\/\/[a-zA-Z0-9.-]+(?::\d+)...Relative URL
Relative URL path starting with /
^\/[^\s]*$Absolute URL
Absolute URL with any protocol scheme
^[a-zA-Z][a-zA-Z0-9+.-]*:\/\/[^\s]+$Code
JavaScript Variable Name
Valid JavaScript variable/identifier name
^[a-zA-Z_$][a-zA-Z0-9_$]*$Python Variable Name
Valid Python identifier name
^[a-zA-Z_][a-zA-Z0-9_]*$CSS Class Name
Valid CSS class name (starts with letter, underscore, or hyphen)
^-?[_a-zA-Z][_a-zA-Z0-9-]*$CSS ID Selector
CSS ID selector starting with #
^#[_a-zA-Z][_a-zA-Z0-9-]*$JSON Key
JSON object key (quoted string followed by colon)
"([^"\\]*(?:\\.[^"\\]*)*)"\s*:Semantic Version (Strict)
Strict semantic versioning (MAJOR.MINOR.PATCH)
^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*...SemVer with Pre-release
Full semantic version with optional pre-release and build metadata
^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*...JavaScript Import Statement
ES module import statement in JavaScript/TypeScript
^import\s+(?:\{[^}]*\}|[a-zA-Z_$][\w$]*)...JavaScript Require Statement
CommonJS require statement in Node.js
(?:const|let|var)\s+(?:\{[^}]*\}|[a-zA-Z...Python Import Statement
Python import or from...import statement
^(?:from\s+[a-zA-Z_][a-zA-Z0-9_.]*\s+)?i...SQL SELECT Statement
Basic SQL SELECT...FROM statement
^\s*SELECT\s+.+\s+FROM\s+\w+Docker Image Tag
Docker image name with optional registry and tag
^(?:[a-z0-9]+(?:[._-][a-z0-9]+)*\/)*[a-z...npm Package Name
Valid npm package name (scoped or unscoped)
^(?:@[a-z0-9-~][a-z0-9-._~]*\/)?[a-z0-9-...Cron Expression (5-field)
Standard 5-field cron expression (min hour dom month dow)
^(?:[0-9*,/-]+\s+){4}[0-9*,/-]+$Cron Expression (6-field Quartz)
6-field Quartz/Spring cron expression with seconds
^(?:[0-9*,/-]+\s+){5}[0-9*,/?L#-]+$Environment Variable Name
Standard environment variable name (uppercase with underscores)
^[A-Z_][A-Z0-9_]*$Dotenv Line
.env file line (KEY=value format)
^[A-Z_][A-Z0-9_]*=.*$Dockerfile Instruction
Dockerfile instruction keyword at start of line
^(?:FROM|RUN|CMD|LABEL|MAINTAINER|EXPOSE...Kubernetes Label
Kubernetes label key with optional prefix (prefix/name)
^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-z...Docker Container ID
Docker container ID (short 12 or full 64 hex chars)
^[0-9a-f]{12}(?:[0-9a-f]{52})?$SemVer Range (npm-style)
npm-style version range with optional ~ or ^ prefix
^[~^]?(0|[1-9]\d*)(?:\.(0|[1-9]\d*)(?:\....package.json Script
package.json script entry ("name": "command")
"([a-zA-Z0-9:_-]+)"\s*:\s*"([^"]*)"Makefile Target
Makefile target definition (name followed by colon)
^[a-zA-Z0-9_.-]+\s*:(?!=)JSON Boolean
JSON boolean literal (true or false)
^(?:true|false)$JSON Null
JSON null literal
^null$Git Version Tag
Git version tag with optional v prefix (v1.0.0 or 1.0.0)
^v?(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\...Text Processing
Markdown Heading
Markdown heading (# to ######)
^#{1,6}\s+.+$Markdown Link
Markdown inline link [text](url)
\[([^\]]+)\]\(([^)]+)\)Markdown Image
Markdown inline image 
!\[([^\]]*)\]\(([^)]+)\)Markdown Bold
Markdown bold text (**text** or __text__)
\*\*([^*]+)\*\*|__([^_]+)__Markdown Code Block
Markdown fenced code block opening/closing delimiter
^```(?:[a-zA-Z]*)?$camelCase Word
camelCase identifier (starts lowercase, no separators)
^[a-z][a-zA-Z0-9]*$snake_case Word
snake_case identifier (lowercase with underscores)
^[a-z][a-z0-9]*(?:_[a-z0-9]+)+$kebab-case Word
kebab-case identifier (lowercase with hyphens)
^[a-z][a-z0-9]*(?:-[a-z0-9]+)+$PascalCase Word
PascalCase identifier (starts uppercase, no separators)
^[A-Z][a-zA-Z0-9]*$SCREAMING_SNAKE_CASE
SCREAMING_SNAKE_CASE constant name (uppercase with underscores)
^[A-Z][A-Z0-9]*(?:_[A-Z0-9]+)+$Repeated Words
Detects consecutive duplicate words (e.g. "the the")
\b(\w+)\s+\1\bEmoji Detection
Detects common emoji characters in text
[\u{1F600}-\u{1F64F}\u{1F300}-\u{1F5FF}\...LaTeX Command
LaTeX command with optional braced arguments
\\[a-zA-Z]+(?:\{[^}]*\})*LaTeX Inline Math
LaTeX inline math delimited by single dollar signs
\$[^$]+\$ASCII Only String
String containing only ASCII characters (0-127)
^[\x00-\x7F]+$Non-ASCII Characters
Detects any non-ASCII character in text
[^\x00-\x7F]