Regex Pattern Library

A curated collection of regular expressions for everyday development tasks. Copy, paste, and understand exactly how these patterns validate and extract data.

Dates & Numbers

ISO 8601 Date Validation

/^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])$/

Validates dates in ISO 8601 format (YYYY-MM-DD).

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24-Hour Time Validation

/^([01]\d|2[0-3]):([0-5]\d)(?::([0-5]\d))?$/

Validates time in 24-hour format (HH:MM or HH:MM:SS).

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Currency Amount Validation

/^\$?\d{1,3}(?:,\d{3})*(?:\.\d{2})?$/

Validates US currency amounts like $1,234.56 or 1234.56.

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ISO 8601 Datetime with UTC Z

/^[0-9]{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12][0-9]|3[01])T(?:[01][0-9]|2[0-3]):[0-5][0-9]:[0-5][0-9](?:\.[0-9]+)?Z$/

Matches an ISO 8601 datetime in UTC (Z suffix).

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Unix Timestamp (Seconds)

Matches a 10-digit Unix timestamp in seconds (the 2001–2286 range).

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Unix Timestamp (Milliseconds)

Matches a 13-digit Unix timestamp in milliseconds.

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ISO 8601 Duration

/^P(?!$)(?:[0-9]+Y)?(?:[0-9]+M)?(?:[0-9]+W)?(?:[0-9]+D)?(?:T(?:[0-9]+H)?(?:[0-9]+M)?(?:[0-9]+(?:\.[0-9]+)?S)?)?$/

Matches an ISO 8601 duration (PT1H30M, P3D, P1Y2M3DT4H5M6S).

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Scientific Notation Number

/^[-+]?[0-9]+(?:\.[0-9]+)?(?:[eE][-+]?[0-9]+)?$/

Matches a numeric literal in optional scientific notation (1e9, 3.14e-2).

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Binary Number (0b prefix)

Matches a binary literal in the 0b... form (JS, Python, Rust).

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Hexadecimal Number (0x prefix)

/^0x[0-9a-fA-F]+$/

Matches a 0x-prefixed hex literal.

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Extraction

URL Extraction

/https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)/g

Extract URLs starting with http or https from a larger block of text.

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Markdown Link Extraction

/\[([^\[\]]+)\]\((https?:\/\/[^\s)]+)\)/g

Extracts Markdown inline links, capturing both the link text and the URL.

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HTML Tag Extraction

/<([a-zA-Z][a-zA-Z0-9]*)(?:\s[^>]*)?>/g

Extracts opening HTML tags and their tag names from an HTML string.

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HTML Comment Extraction

//g

Extracts HTML comments from an HTML string.

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HTML Heading Tag Extraction

/<h([1-6])[^>]*>(.*?)<\/h\1>/gi

Extracts HTML heading tags (h1-h6) and their text content.

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YouTube Video ID

/^[a-zA-Z0-9_-]{11}$/

Validates an 11-character YouTube video ID.

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YouTube URL, Extract Video ID

/(?:youtube\.com/(?:watch\?v=|embed/|shorts/|v/)|youtu\.be/)([a-zA-Z0-9_-]{11})/i

Extracts the 11-char video ID from any common YouTube URL shape.

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JSON String Literal

/"(?:[^"\\\x00-\x1f]|\\["\\/bfnrt]|\\u[0-9a-fA-F]{4})*"/

Matches a single JSON-encoded string literal per RFC 8259.

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ANSI Escape Sequence (Terminal Control)

/\x1b\[[0-9;?]*[A-Za-z]/

Matches an ANSI escape sequence (e.g., color codes, cursor movement).

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File & Path

Windows File Path Validation

/^[a-zA-Z]:\\(?:[^\\/:*?"<>|\r\n]+\\)*[^\\/:*?"<>|\r\n]*$/

Validates Windows absolute file paths like C:\Users\name\file.txt.

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Unix/Linux File Path Validation

/^(\/[^\/\x00]+)+\/?$/

Validates Unix absolute file paths like /usr/local/bin/node.

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Windows Drive Letter Path

/^[A-Za-z]:[\\/]/

Matches the prefix of a Windows drive-letter absolute path (C:\... or C:/...).

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Security

Strong Password Validation

/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$/

Validates a strong password (min 8 chars, 1 uppercase, 1 lowercase, 1 number, 1 special char).

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Credit Card Number Validation

/^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|3[47][0-9]{13}|6(?:011|5[0-9]{2})[0-9]{12})$/

Validates Visa, Mastercard, American Express, and Discover card numbers (digits only, no spaces).

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JWT Format Validation

/^[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]*$/

Validates that a string has the three-part Base64URL structure of a JSON Web Token.

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Generic API Key Format Validation

/^[A-Za-z0-9_\-]{20,64}$/

Validates generic API keys: 20-64 alphanumeric characters with underscores and hyphens.

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Password Without Spaces

Validates that a password is at least 8 characters with no spaces.

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Stripe Secret API Key

/^sk_(test|live)_[A-Za-z0-9]{24,99}$/

Detects a Stripe secret API key. Useful for secret-scanning hooks.

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JWT Three-Segment Structure

/^[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+$/

Validates the three-segment base64url shape of a JWT, header.payload.signature.

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Redacted Token Marker

/^(?:[*]{4,}|REDACTED|<redacted>|\[REDACTED\])$/i

Matches common log-redaction markers used to scrub secrets.

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Validation

Email Address Validation

/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/

A standard regex pattern to validate most common email address formats.

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Hexadecimal Color Validation

/^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$/

Validates 3-digit and 6-digit hex color codes.

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Phone Number (E.164 International)

/^\+[1-9]\d{1,14}$/

Validates international phone numbers in E.164 format (e.g. +14155552671).

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US Phone Number Validation

/^(\+1)?[-.\s]?\(?[2-9]\d{2}\)?[-.\s]?\d{3}[-.\s]?\d{4}$/

Validates US phone numbers in common formats including (555) 555-5555, 555-555-5555, and +1 555 555 5555.

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UUID v4 Validation

/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i

Validates a UUID version 4 (randomly generated) in standard hyphenated format.

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Semantic Version (SemVer) Validation

/^(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-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$/

Validates semantic version strings like 1.2.3, 1.0.0-alpha.1, and 2.0.0+build.123.

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US Social Security Number (SSN)

/^(?!000|666|9\d{2})\d{3}-(?!00)\d{2}-(?!0000)\d{4}$/

Validates US Social Security Numbers in the standard XXX-XX-XXXX format.

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US ZIP Code Validation

/^\d{5}(?:-\d{4})?$/

Validates US ZIP codes in 5-digit (12345) and ZIP+4 (12345-6789) formats.

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Base64 String Validation

/^(?:[A-Za-z0-9+\/]{4})*(?:[A-Za-z0-9+\/]{2}==|[A-Za-z0-9+\/]{3}=)?$/

Validates standard Base64-encoded strings including padding.

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Docker Image Tag Validation

/^[a-z0-9]+(?:[._-][a-z0-9]+)*(?:\/[a-z0-9]+(?:[._-][a-z0-9]+)*)*(?::[a-zA-Z0-9._-]+)?$/

Validates Docker image references like nginx:latest, myrepo/myimage:1.0.0, or registry.example.com/org/image:tag.

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Environment Variable Name Validation

/^[A-Z_][A-Z0-9_]*$/

Validates POSIX-compliant environment variable names: uppercase letters, digits, and underscores, not starting with a digit.

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Git Commit Hash Validation

/^[0-9a-f]{7,40}$/i

Validates Git commit hashes in short (7-char) or full (40-char) SHA-1 format.

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Username Validation

/^[a-zA-Z0-9_-]{3,20}$/

Validates usernames: 3–20 characters, letters, numbers, underscores, and hyphens only.

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Twitter/X Handle Validation

/^@?[A-Za-z0-9_]{1,15}$/

Validates Twitter/X handles with optional @ prefix, 1-15 alphanumeric characters and underscores.

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CSS Class Name Validation

/^-?[_a-zA-Z]+[_a-zA-Z0-9-]*$/

Validates CSS class names per the CSS specification.

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AWS S3 Bucket Name Validation

/^[a-z0-9][a-z0-9.-]{1,61}[a-z0-9]$/

Validates AWS S3 bucket names per AWS naming rules.

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npm Package Name Validation

/^(?:@[a-z0-9-*~][a-z0-9-*._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$/

Validates npm package names including scoped packages like @org/package.

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SQL Identifier Validation

/^[a-zA-Z_][a-zA-Z0-9_]*$/

Validates SQL identifiers (table names, column names): letters, digits, and underscores, not starting with a digit.

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CSS RGB Color Validation

/^rgb\(\s*(\d{1,3})\s*,\s*(\d{1,3})\s*,\s*(\d{1,3})\s*\)$/

Validates CSS rgb() color values like rgb(255, 128, 0).

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Git Branch Name Validation

/^(?!.*\.\.)(?!.*@\{)(?!.*\\)(?!.*[~^:?*\[\] ])(?!.*\.lock$)(?!\/|.*\/$)(?!.*\/\/)(?!.*\.$)[^\x00-\x1f\x7f]+$/

Validates Git branch names per git check-ref-format rules.

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MIME Type Validation

/^[a-zA-Z0-9][a-zA-Z0-9!#$&\-^_]*\/[a-zA-Z0-9][a-zA-Z0-9!#$&\-^_.+]*$/

Validates MIME type strings like text/html, application/json, image/png.

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CSS HSL Color Validation

/^hsl\(\s*(\d{1,3})\s*,\s*(\d{1,3})%\s*,\s*(\d{1,3})%\s*\)$/

Validates CSS hsl() color values like hsl(120, 100%, 50%).

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Latitude/Longitude Coordinate Validation

/^(-?(?:90(?:\.0+)?|(?:[0-8]?\d)(?:\.\d+)?)),\s*(-?(?:180(?:\.0+)?|(?:1[0-7]\d|[0-9]?\d)(?:\.\d+)?))$/

Validates a latitude,longitude coordinate pair like 37.7749,-122.4194.

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ISBN-13 Validation

/^(?:978|979)-?\d{1,5}-?\d{1,7}-?\d{1,6}-?\d$/

Validates ISBN-13 book identifiers starting with 978 or 979.

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Docker Container Name Validation

/^[a-zA-Z0-9][a-zA-Z0-9_.-]+$/

Validates Docker container names: alphanumeric, underscores, dots, and hyphens.

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YAML Key Validation

/^[a-zA-Z_][a-zA-Z0-9_-]*$/

Validates simple YAML keys: letters, digits, underscores, and hyphens, starting with a letter or underscore.

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UK Phone Number Validation

/^(\+44|0)7\d{9}$/

Validates UK mobile phone numbers in +447xxxxxxxxx or 07xxxxxxxxx format.

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Indian Phone Number Validation

/^(\+91|0)?[6-9]\d{9}$/

Validates Indian mobile phone numbers with optional +91 or 0 prefix.

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Stripe Customer ID

/^cus_[A-Za-z0-9]{14,24}$/

Validates a Stripe Customer ID (cus_XXXXXXXXXXXXXX).

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Stripe Charge ID

/^ch_[A-Za-z0-9]{24,32}$/

Validates a Stripe Charge ID (ch_XXXXXXXX...).

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Stripe Payment Intent ID

/^pi_[A-Za-z0-9]{24,32}$/

Validates a Stripe Payment Intent ID (pi_XXXXXXXX...).

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GitHub Username

/^[a-zA-Z0-9](?:[a-zA-Z0-9]|-(?=[a-zA-Z0-9])){0,38}$/

Validates a GitHub username per GitHub's documented rules.

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GitHub owner/repo Path

/^[a-zA-Z0-9](?:[a-zA-Z0-9]|-(?=[a-zA-Z0-9])){0,38}/[a-zA-Z0-9._-]{1,100}$/

Matches a GitHub owner/repository path like 'torvalds/linux'.

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Git Short SHA (7 hex)

/^[0-9a-f]{7}$/

Matches a 7-character abbreviated Git commit SHA.

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MongoDB ObjectId

/^[0-9a-fA-F]{24}$/

Validates a MongoDB ObjectId, 24 hex characters.

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ULID Identifier

/^[0-9A-HJKMNP-TV-Z]{26}$/

Validates a ULID (Universally Unique Lexicographically Sortable Identifier).

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NanoID

/^[A-Za-z0-9_-]{21}$/

Validates a default 21-character NanoID.

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Bitcoin Address (P2PKH, P2SH, Bech32)

/^(?:[13][a-km-zA-HJ-NP-Z1-9]{25,34}|bc1[a-z0-9]{39,59})$/

Matches legacy (1...), P2SH (3...), and Bech32 (bc1...) Bitcoin addresses.

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Ethereum Address

/^0x[a-fA-F0-9]{40}$/

Validates a hex-encoded Ethereum address (40 hex chars, 0x-prefixed).

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Vimeo Video ID

/^[0-9]{6,12}$/

Validates a Vimeo video ID, 6–12 digits.

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UK Postal Code

/^[A-Z]{1,2}[0-9][A-Z0-9]? ?[0-9][A-Z]{2}$/i

Validates a UK postal code (postcode) with optional space.

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Canadian Postal Code

/^[ABCEGHJ-NPRSTVXY][0-9][A-Z] ?[0-9][A-Z][0-9]$/i

Validates a Canadian postal code (A1A 1A1).

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India Pincode

/^[1-9][0-9]{5}$/

Validates an Indian 6-digit PIN code.

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ISO 3166-1 alpha-2 Country Code

Matches a 2-letter uppercase ISO country code (US, GB, IN, ...).

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ISO 4217 Currency Code

Matches a 3-letter uppercase ISO currency code (USD, EUR, GBP, ...).

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ISO 639-1 Language Code

/^[a-z]{2}(?:-[A-Z]{2})?$/

Matches a 2-letter language code with optional region (en, en-US, pt-BR).

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JSON Pointer (RFC 6901)

/^(?:/(?:[^/~]|~0|~1)*)*$/

Validates a JSON Pointer string per RFC 6901.

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Python Identifier

/^[A-Za-z_][A-Za-z0-9_]*$/

Matches a Python identifier (ASCII; PEP 8 ASCII recommendation).

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Go Module Path

/^(?:[a-zA-Z0-9.-]+(?:\.[a-zA-Z0-9-]+)+)(?:/[a-zA-Z0-9._~-]+)+$/

Matches a Go module import path (e.g., github.com/anthropics/claude-code).

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Rust Crate Name

/^[a-zA-Z][a-zA-Z0-9_-]{0,63}$/

Validates a Rust crate name as accepted by crates.io.

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Java Package Name

/^(?:[a-z][a-z0-9_]*)(?:\.[a-z][a-z0-9_]*)+$/

Validates a Java package name (lowercase segments separated by dots).

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Tracking ID (UUID v4 or ULID)

/^(?:[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}|[0-9A-HJKMNP-TV-Z]{26})$/i

Matches either a UUID v4 or a ULID, common identifiers in distributed tracing.

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Web & Network

IPv4 Address Validation

/^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/

Validates a standard dotted-decimal IPv4 address.

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IPv6 Address Validation

/^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$/

Validates a full (non-compressed) IPv6 address in colon-hexadecimal notation.

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URL Slug Validation

/^[a-z0-9]+(?:-[a-z0-9]+)*$/

Validates a URL-safe slug: lowercase letters, numbers, and hyphens only, no leading/trailing hyphens.

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CIDR Notation Validation

/^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\/([0-9]|[1-2][0-9]|3[0-2])$/

Validates IPv4 CIDR notation like 192.168.1.0/24.

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MAC Address Validation

/^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$/

Validates MAC addresses in colon-separated (AA:BB:CC:DD:EE:FF) or hyphen-separated (AA-BB-CC-DD-EE-FF) formats.

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Data URI Validation

/^data:([a-zA-Z0-9][a-zA-Z0-9!#$&\-^_]*\/[a-zA-Z0-9][a-zA-Z0-9!#$&\-^_]*)(;base64)?,/

Validates data URIs like data:image/png;base64, or data:text/plain,.

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Network Port Number Validation

/^([1-9]\d{0,3}|[1-5]\d{4}|6[0-4]\d{3}|65[0-4]\d{2}|655[0-2]\d|6553[0-5])$/

Validates TCP/UDP port numbers in the valid range 1-65535.

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Stripe Publishable API Key

/^pk_(test|live)_[A-Za-z0-9]{24,99}$/

Matches a Stripe publishable key (safe to expose in client-side code).

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AWS ARN

/^arn:(?:aws|aws-cn|aws-us-gov):[a-zA-Z0-9-]+:[a-z0-9-]*:[0-9]*:.+$/

Matches the structure of an AWS Amazon Resource Name (ARN).

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AWS Account ID

Validates a 12-digit AWS account ID.

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Hex Color With Optional Alpha (#RGB / #RGBA / #RRGGBB / #RRGGBBAA)

/^#(?:[0-9a-fA-F]{3,4}|[0-9a-fA-F]{6}|[0-9a-fA-F]{8})$/

Matches modern CSS hex colors including 3, 4, 6, or 8 hex digits (alpha-channel forms).

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CSS rgba() Color

/^rgba\(\s*(?:\d{1,3})\s*,\s*(?:\d{1,3})\s*,\s*(?:\d{1,3})\s*,\s*(?:0|1|0?\.\d+)\s*\)$/

Validates a CSS rgba(r, g, b, a) color string.

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CSS hsla() Color

/^hsla\(\s*(?:\d{1,3})(?:deg)?\s*,\s*(?:\d{1,3})%\s*,\s*(?:\d{1,3})%\s*,\s*(?:0|1|0?\.\d+)\s*\)$/

Validates a CSS hsla(h, s, l, a) color string.

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Data URL (data:)

/^data:[a-zA-Z0-9!#$&\-^_+.]+/[a-zA-Z0-9!#$&\-^_+.]+(;[a-zA-Z0-9-]+=[a-zA-Z0-9-]+)*(;base64)?,.+$/

Matches a data: URL with MIME type, optional parameters, optional base64 flag, and payload.

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IPv4 CIDR Block

/^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)/(?:3[0-2]|[12]?[0-9])$/

Validates an IPv4 address with a /0–/32 CIDR suffix.

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IPv6 CIDR Block

/^[0-9a-fA-F:]+/(?:12[0-8]|1[01][0-9]|[1-9]?[0-9])$/

Matches an IPv6 address (loosely) with a /0–/128 mask.

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Kubernetes Resource Name (DNS subdomain)

/^[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*$/

Validates a Kubernetes resource name following the RFC 1123 DNS subdomain rules.

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Kubernetes Label Value

/^(?:[a-zA-Z0-9](?:[a-zA-Z0-9_.-]{0,61}[a-zA-Z0-9])?)?$/

Validates a Kubernetes label value, up to 63 chars, alphanumeric/dot/underscore/hyphen.

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URI Scheme Prefix

/^[a-zA-Z][a-zA-Z0-9+.-]*:/

Matches the scheme part of a URI per RFC 3986.

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Open Graph Image URL

/^https?://[^\s"<>]+\.(?:jpe?g|png|webp|gif|svg)(?:\?[^\s"<>]*)?$/i

Matches a remote image URL suitable for Open Graph meta tags.

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