Balanced Parentheses
/\([^()]*\)/g
Use: Expression parsing, code analysis, mathematical expressions · Lang: Universal · Match: (hello world)
Lookahead (Positive)
/\w+(?=\s+is)/g
Use: Context-dependent matching, NLP, text analysis · Lang: Universal · Match: JavaScript is awesome
Lookbehind (Positive)
/(?<=\$)\d+(\.\d{2})?/g
Use: Price extraction, financial data parsing, currency processing · Lang: JavaScript · Match: Price: $49.99
Named Capture Groups
/(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/
Use: Structured data extraction, code readability, date parsing · Lang: JavaScript · Match: 2026-03-07
Non-Greedy Matching
/<.+?>/g
Use: HTML parsing, tag matching, minimal matching · Lang: Universal · Match: <b>bold</b>
Atomic Group Simulation
/(?=(\d+))\1\s/g
Use: Performance optimization, backtracking prevention · Lang: JavaScript · Match: 123
Conditional with Alternation
/(?:https?|ftp):\/\/\S+/g
Use: Protocol-specific URL matching, link classification · Lang: Universal · Match: Visit ftp://files.example.com
Recursive Pattern (Email List)
/[\w.+-]+@[\w-]+\.[\w.]+(?:\s*,\s*[\w.+-]+@[\w-]+\.[\w.]+)*/
JavaScript Variable
/\b(const|let|var)\s+([a-zA-Z_$][a-zA-Z0-9_$]*)\b/g
Use: Code analysis, linting, refactoring tools · Lang: JavaScript · Match: const myVar = 5
JavaScript Function
/\bfunction\s+([a-zA-Z_$][a-zA-Z0-9_$]*)\s*\(/g
Use: Code indexing, documentation generation, IDE features · Lang: JavaScript · Match: function calculateTax(
CSS Hex Color
/#([0-9a-fA-F]{3}){1,2}\b/g
Use: Design tools, theme extraction, CSS processing · Lang: CSS · Match: #FF5733
CSS Class Selector
/\.[a-zA-Z_][a-zA-Z0-9_-]*/g
Use: CSS analysis, class extraction, style auditing · Lang: CSS · Match: .my-class
Python Import
/^(?:from\s+[\w.]+\s+)?import\s+[\w.,\s]+$/gm
Use: Dependency analysis, code refactoring, import sorting · Lang: Python · Match: from os.path import join
SQL SELECT Statement
/\bSELECT\b[\s\S]+?\bFROM\b\s+\w+/gi
Use: Query logging, SQL injection detection, query optimization · Lang: SQL · Match: SELECT * FROM users
JSON Key-Value Pair
/"([^"]+)"\s*:\s*("([^"]*)"|\d+|true|false|null)/g
Use: JSON parsing, data extraction, API response processing · Lang: JSON · Match: "name": "John"
TODO Comment
/\/\/\s*(TODO|FIXME|HACK|XXX|BUG):\s*(.+)$/gm
Use: Code review, technical debt tracking, IDE integration · Lang: Universal · Match: // TODO: Fix this later
Semantic Version
/^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(-[a-zA-Z0-9.]+)?(\+[a-zA-Z0-9.]+)?$/
Use: Package management, CI/CD, release automation · Lang: Universal · Match: 2.1.0-beta.1
Git Commit Hash
/^[0-9a-f]{7,40}$/
Use: Git automation, CI/CD pipelines, commit referencing · Lang: Universal · Match: a1b2c3d
Environment Variable
/^[A-Z][A-Z0-9_]*=.+$/gm
Use: .env file parsing, configuration management, deployment · Lang: Universal · Match: DATABASE_URL=postgres://localhost
Import Path
/['"]([./]\S+?)['"]/g
Use: Dependency graph, path resolution, bundle analysis · Lang: Universal · Match: import x from './utils'
JSON Object
/\{[\s\S]*\}/
Use: JSON detection, API response parsing, log analysis · Lang: Universal · Match: {"key": "value"}
CSV Row
/^("(?:[^"]|"")*"|[^,]*)(,("(?:[^"]|"")*"|[^,]*))*$/gm
Use: CSV parsing, data import, spreadsheet processing · Lang: Universal · Match: "John","Doe",30
XML Tag with Content
/<(\w+)[^>]*>(.*?)<\/\1>/gs
Use: XML parsing, data extraction, SOAP processing · Lang: Universal · Match: <name>John</name>
YAML Key-Value
/^([\w.-]+):\s+(.+)$/gm
Use: Configuration parsing, Docker Compose, Kubernetes manifests · Lang: Universal · Match: name: John Doe
Log Entry (Common Log Format)
/^(\S+)\s+(\S+)\s+(\S+)\s+\[([^\]]+)\]\s+"(\S+)\s+(\S+)\s+(\S+)"\s+(\d+)\s+(\d+)/gm
Use: Log analysis, monitoring, security investigation · Lang: Universal · Match: 127.0.0.1 - - [07/Mar/2026:14:00:00 +0000] "GET /index.html HTTP/1.1" 200 1234
INI Section
/^\[([^\]]+)\]$/gm
Use: Configuration file parsing, INI processing, settings management · Lang: Universal · Match: [database]
TOML Key-Value
/^([a-zA-Z_][a-zA-Z0-9_]*)\s*=\s*(.+)$/gm
Use: Cargo.toml parsing, config management, Rust ecosystem · Lang: Universal · Match: port = 8080
SQL Comment
/--.*$|\/\*[\s\S]*?\*\//gm
Use: SQL cleanup, query extraction, code documentation · Lang: SQL · Match: -- This is a comment
Docker Image Reference
/^([a-z0-9._-]+\/)?[a-z0-9._-]+(:[a-zA-Z0-9._-]+)?(@sha256:[a-f0-9]{64})?$/
Use: Dockerfile linting, container orchestration, CI/CD · Lang: Universal · Match: nginx:latest
File Path (Unix)
/^\/(?:[a-zA-Z0-9._-]+\/?)*$/
Use: Path validation, file system operations, log parsing · Lang: Universal · Match: /usr/local/bin/node
Date (YYYY-MM-DD)
/^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$/
Use: ISO 8601 date validation, database input, API payloads · Lang: Universal · Match: 2026-03-07
Date (MM/DD/YYYY)
/^(0[1-9]|1[0-2])\/(0[1-9]|[12]\d|3[01])\/\d{4}$/
Use: US date format validation, form inputs, data parsing · Lang: Universal · Match: 03/07/2026
Date (DD/MM/YYYY)
/^(0[1-9]|[12]\d|3[01])\/(0[1-9]|1[0-2])\/\d{4}$/
Use: European/international date validation, localization · Lang: Universal · Match: 07/03/2026
Time (24-hour)
/^([01]\d|2[0-3]):[0-5]\d(:[0-5]\d)?$/
Use: Time input validation, scheduling, log timestamps · Lang: Universal · Match: 23:59:59
Time (12-hour)
/^(0?[1-9]|1[0-2]):[0-5]\d\s?[AaPp][Mm]$/
Use: US time display, scheduling apps, time picker validation · Lang: Universal · Match: 2:30 PM
ISO 8601 DateTime
/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?(Z|[+-]\d{2}:\d{2})?$/
Use: API timestamps, logging, database datetime fields · Lang: Universal · Match: 2026-03-07T14:30:00Z
Unix Timestamp
/^\d{10,13}$/
Use: API responses, database records, log analysis · Lang: Universal · Match: 1678185600000
Relative Date
/^\d+\s+(second|minute|hour|day|week|month|year)s?\s+(ago|from now)$/i
Use: Natural language date parsing, social media timestamps, UX · Lang: Universal · Match: 5 days ago
Duration (HH:MM:SS)
/^\d+:[0-5]\d:[0-5]\d$/
Use: Video duration, timer display, time tracking · Lang: Universal · Match: 01:30:45
Cron Expression
/^(\*|\d+|\d+-\d+|\d+\/\d+)(\s+(\*|\d+|\d+-\d+|\d+\/\d+)){4}$/
Use: Task scheduling, CI/CD pipelines, system administration · Lang: Universal · Match: 0 */6 * * *
Docker Image Reference
/^(?:([a-z0-9]+(?:[._-][a-z0-9]+)*)\/)?([a-z0-9]+(?:[._-][a-z0-9]+)*)(?::([a-zA-Z0-9][a-zA-Z0-9._-]{0,127}))?(?:@sha256:[a-fA-F0-9]{64})?$/
Use: Container deployment, CI/CD pipelines, registry management · Lang: Universal · Match: nginx:latest
Kubernetes Resource Name
/^[a-z0-9]([a-z0-9-]{0,61}[a-z0-9])?$/
Use: K8s manifest validation, resource naming, CI/CD · Lang: Universal · Match: my-deployment-v2
File Extension
/\.(\w{1,10})$/
Use: File type detection, upload validation, file sorting · Lang: Universal · Match: document.pdf
Image File
/\.(jpe?g|png|gif|svg|webp|bmp|ico|tiff?)$/i
Use: Upload validation, file filtering, media processing · Lang: Universal · Match: photo.jpg
Video File
/\.(mp4|avi|mkv|mov|wmv|flv|webm|m4v|mpeg)$/i
Use: Media upload validation, file management, streaming · Lang: Universal · Match: video.mp4
File Path (Windows)
/^[a-zA-Z]:\\(?:[^\\/:*?"<>|]+\\)*[^\\/:*?"<>|]*$/
Use: Windows path validation, cross-platform tools, file operations · Lang: Universal · Match: C:\Users\Documents\file.txt
MIME Type
/^(application|audio|font|image|message|model|multipart|text|video)\/[a-zA-Z0-9][a-zA-Z0-9!#$&\-^_.+]*$/
Use: Content-Type validation, file upload handling, API headers · Lang: Universal · Match: application/json
S3 Bucket URL
/s3:\/\/([a-z0-9][a-z0-9.-]{1,61}[a-z0-9])(\/.*)?/
Use: AWS infrastructure, cloud storage, data pipelines · Lang: Universal · Match: s3://my-bucket/path/to/file.txt
Mastercard Credit Card Number
/^(?:5[1-5][0-9]{2}|222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[0-9]{12}$/
Use: Payment validation, transaction processing · Lang: Universal · Match: 5500000000000004
Visa Credit Card Number
/^4[0-9]{12}(?:[0-9]{3})?$/
Use: Payment validation, fraud detection · Lang: Universal · Match: 4111111111111111
Social Security Number (US)
/^\d{3}-\d{2}-\d{4}$/
Use: PII detection, data masking, compliance scanning · Lang: Universal · Match: 123-45-6789
US Zip Code
/^\d{5}(-\d{4})?$/
Use: Address validation, shipping forms, location services · Lang: Universal · Match: 90210-1234
US State Code
/^(A[KLRZ]|C[AOT]|D[CE]|FL|GA|HI|I[ADLN]|K[SY]|LA|M[ADEINOST]|N[CDEHJMVY]|O[HKR]|PA|RI|S[CD]|T[NX]|UT|V[AIT]|W[AIVY])$/
Use: Address forms, state selection validation, data cleaning · Lang: Universal · Match: CA
UK Postcode
/^[A-Z]{1,2}\d[A-Z\d]?\s?\d[A-Z]{2}$/i
Use: UK address validation, shipping, location services · Lang: Universal · Match: SW1A 1AA
Canadian Postal Code
/^[A-Z]\d[A-Z]\s?\d[A-Z]\d$/i
Use: Canadian address validation, shipping, geolocation · Lang: Universal · Match: K1A 0B1
Passport Number
/^[A-Z]{1,2}\d{6,9}$/
Use: Travel document validation, KYC compliance, identity verification · Lang: Universal · Match: AB1234567
IBAN Number
/^[A-Z]{2}\d{2}[A-Z0-9]{4}\d{7}([A-Z0-9]?){0,16}$/
Use: Banking, international transfers, payment processing · Lang: Universal · Match: GB29NWBK60161331926819
VIN (Vehicle Identification Number)
/^[A-HJ-NPR-Z0-9]{17}$/
Use: Automotive, insurance, vehicle registration, fraud detection · Lang: Universal · Match: 1HGBH41JXMN109186
Integer
/^-?\d+$/
Use: Input validation, number parsing, data filtering · Lang: Universal · Match: -42
Decimal Number
/^-?\d+\.?\d*$/
Use: Numeric input validation, scientific data, calculations · Lang: Universal · Match: 3.14159
Currency (USD)
/^\$?\d{1,3}(,\d{3})*(\.\d{2})?$/
Use: Financial data parsing, invoice processing, price extraction · Lang: Universal · Match: $1,234.56
Percentage
/^-?\d+(\.\d+)?%$/
Use: Data validation, statistics, report parsing · Lang: Universal · Match: 99.9%
Hexadecimal Number
/^(0x)?[0-9a-fA-F]+$/
Use: 0x literals, memory addresses, byte strings, CSS color validation, binary data representation · Lang: Universal · Match: 0xFF00FF
Binary Number
/^(0b)?[01]+$/
Use: Binary data, bitwise operations, computer science education · Lang: Universal · Match: 0b10110
Scientific Notation
/^-?\d+(\.\d+)?[eE][+-]?\d+$/
Use: Scientific computing, data analysis, engineering calculations · Lang: Universal · Match: 6.022e23
Credit Card Number
/^(?:4\d{12}(?:\d{3})?|5[1-5]\d{14}|3[47]\d{13}|6(?:011|5\d{2})\d{12})$/
Use: Payment form validation, PCI compliance, fraud detection · Lang: Universal · Match: 4111111111111111
SQL Injection Pattern
/(?:--|;|\b(?:SELECT|INSERT|UPDATE|DELETE|DROP|UNION|ALTER)\b)/
Log Level
/\b(DEBUG|INFO|WARN|ERROR|FATAL|TRACE)\b/
Semantic Version
/^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?$/
Terraform Resource Reference
/\b(?:aws|azurerm|google)_[a-z_]+\.[a-z_]+/
GraphQL Query
/\b(query|mutation|subscription)\s+\w+/
GitHub Repository URL
/https?://github\.com/[A-Za-z0-9_.-]+/[A-Za-z0-9_.-]+/
NPM Package Name
/^(@[a-z0-9-~][a-z0-9-._~]*/)?[a-z0-9-~][a-z0-9-._~]*$/
Docker Image Tag
/^[a-z0-9]+(?:[._-][a-z0-9]+)*(?:/[a-z0-9]+(?:[._-][a-z0-9]+)*)*(?::[a-zA-Z0-9._-]+)?$/
Environment Variable
/^[A-Z_][A-Z0-9_]*=.*$/
SQL Injection Pattern (Basic)
/(?:'\s*(?:OR|AND)\s+.*=.*|;\s*(?:DROP|DELETE|UPDATE|INSERT)\s|UNION\s+SELECT|--\s*$)/i
Use: Web application firewall, input validation, security scanning · Lang: SQL · Match: ' OR 1=1 --
JWT Token
/^[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+$/
Use: Token validation, API authentication, security auditing · Lang: Universal · Match: eyJhbG.eyJzdW.SflKxw
UUID (v4)
/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i
Use: ID validation, database records, API responses · Lang: Universal · Match: 550e8400-e29b-41d4-a716-446655440000
API Key Pattern
/(?:api[_-]?key|apikey|token)[\s]*[=:][\s]*["']?([a-zA-Z0-9_-]{20,})["']?/gi
Use: Secret scanning, code review, security auditing · Lang: Universal · Match: api_key="sk_live_abc123def456ghi789"
AWS Access Key
/(?:AKIA|ABIA|ACCA|ASIA)[0-9A-Z]{16}/
Use: Secret detection, security scanning, compliance checks · Lang: Universal · Match: AKIAIOSFODNN7EXAMPLE
Base64 Encoded String
/^[A-Za-z0-9+/]+={0,2}$/
Use: Data encoding validation, API payloads, image embedding · Lang: Universal · Match: SGVsbG8gV29ybGQ=
MD5 Hash
/^[a-f0-9]{32}$/i
Use: Checksum verification, file integrity, legacy password hashing · Lang: Universal · Match: d41d8cd98f00b204e9800998ecf8427e
SHA-256 Hash
/^[a-f0-9]{64}$/i
Use: File verification, blockchain, digital signatures · Lang: Universal · Match: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
SSH Public Key
/^ssh-(rsa|ed25519|ecdsa)\s+[A-Za-z0-9+/=]+/
Use: SSH key management, server configuration, git authentication · Lang: Universal · Match: ssh-rsa AAAAB3NzaC1yc2EAAA...
Username
/^[a-zA-Z0-9_-]{3,20}$/
Use: User registration, profile validation, social media handles · Lang: Universal · Match: cool_user123
Strong Password
/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$/
Use: Registration forms, password policy enforcement, security audits · Lang: Universal · Match: Pass@word1
Slug (URL-friendly)
/^[a-z0-9]+(-[a-z0-9]+)*$/
Use: URL generation, SEO, CMS, blog platforms · Lang: Universal · Match: my-blog-post-2026
Hashtag
/#[a-zA-Z][a-zA-Z0-9_]*/g
Use: Social media parsing, content tagging, trend analysis · Lang: Universal · Match: #JavaScript #coding
HTML Tag
/<\/?[a-zA-Z][a-zA-Z0-9]*\b[^>]*>/g
Use: HTML parsing, sanitization, template processing, web scraping · Lang: Universal · Match: <div class="test">
HTML Comments
/<!--[\s\S]*?-->/g
Use: Code cleanup, template processing, build tools · Lang: Universal · Match: <!-- comment -->
Quoted String
/(["'])(?:(?!\1|\\).|\\.)*\1/g
Use: Syntax highlighting, code parsing, string extraction · Lang: Universal · Match: "hello world"
Markdown Link
/\[([^\]]+)\]\(([^)]+)\)/g
Use: Markdown parsing, documentation processing, link extraction · Lang: Universal · Match: [Click here](https://example.com)
Markdown Heading
/^(#{1,6})\s+(.+)$/gm
Use: Table of contents generation, document structure analysis · Lang: Universal · Match: ## My Heading
Whitespace Trimmer
/^\s+|\s+$/gm
Use: Text cleanup, input sanitization, data normalization · Lang: Universal · Match: hello
Duplicate Words
/\b(\w+)\s+\1\b/gi
Use: Proofreading, text quality checking, content editing · Lang: Universal · Match: the the
Sentence
/[A-Z][^.!?]*[.!?]/g
Use: NLP preprocessing, text splitting, content analysis · Lang: Universal · Match: This is a sentence.
Email Address
/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/
Phone Number (US)
/^(\+1)?[-.\s]?\(?\d{3}\)?[-.\s]?\d{3}[-.\s]?\d{4}$/
Use: Phone input validation, contact forms, CRM data cleaning · Lang: Universal · Match: (555) 123-4567
Phone Number (International)
/^\+?[1-9]\d{1,14}$/
Use: International phone validation, E.164 format compliance · Lang: Universal · Match: +442071234567
URL
/https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)/
Use: Link validation, web scraping, content parsing · Lang: Universal · Match: https://www.example.com/path?q=1
IPv4 Address
/^((25[0-5]|(2[0-4]|1\d|[1-9]|)\d)\.?\b){4}$/
Use: Network configuration, log parsing, firewall rules · Lang: Universal · Match: 192.168.1.1
IPv6 Address
/^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$/
Use: Network configuration, DNS records, next-gen networking · Lang: Universal · Match: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
MAC Address
/^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$/
Use: Network device identification, DHCP management, security auditing · Lang: Universal · Match: 00:1A:2B:3C:4D:5E
Domain Name
/^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)+[a-zA-Z]{2,}$/
Use: DNS validation, URL parsing, domain registration checks · Lang: Universal · Match: sub.example.com
Email in Text
/[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}/g
Image Tag (src)
/[<]img[^>]+src=["']([^"']+)["']/gi
Use: Image extraction, SEO auditing, accessibility checking · Lang: HTML · Match: <img src="photo.jpg" alt="Photo">
Anchor Tag (href)
/<a[^>]+href=["']([^"']+)["']/gi
Use: Link extraction, site crawling, SEO link auditing · Lang: HTML · Match: <a href="/about/">About</a>
Meta Tag Content
/<meta[^>]+content=["']([^"']+)["']/gi
Use: SEO analysis, social media preview, metadata extraction · Lang: HTML · Match: <meta name="description" content="My site">
Inline CSS Style
/style=["']([^"']+)["']/gi
Use: Code cleanup, CSS extraction, linting · Lang: HTML · Match: <div style="color: red;">
YouTube Video ID
/(?:youtube\.com\/watch\?v=|youtu\.be\/|youtube\.com\/embed\/)([a-zA-Z0-9_-]{11})/g
Use: Video embedding, content curation, social media tools · Lang: Universal · Match: https://www.youtube.com/watch?v=dQw4w9WgXcQ
Twitter/X Handle
/@([a-zA-Z0-9_]{1,15})\b/g
Use: Social media monitoring, mention tracking, user tagging · Lang: Universal · Match: @elonmusk
GitHub Repository URL
/github\.com\/([a-zA-Z0-9_.-]+)\/([a-zA-Z0-9_.-]+)/g
Use: Open source tracking, dependency analysis, documentation · Lang: Universal · Match: https://github.com/facebook/react
CSS Media Query
/@media\s*\([^)]+\)\s*\{/g
Use: Responsive design analysis, CSS auditing, style extraction · Lang: CSS · Match: @media (max-width: 768px) {
Data Attribute
/data-([a-z-]+)=["']([^"']*)["']/gi
Use: DOM manipulation, JavaScript frameworks, testing selectors · Lang: HTML · Match: data-user-id="123"