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Regular Expression (Regex) Reference & Pattern Documenter

Curate, document, and export regex patterns and token syntax into clean GitHub Flavored Markdown reference tables.

Presets:

Active Regex Patterns (5)

/flags:

Regex Pattern Expression

Example Match

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/flags:

Regex Pattern Expression

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/flags:

Regex Pattern Expression

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/flags:

Regex Pattern Expression

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/flags:

Regex Pattern Expression

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Generated Markdown Guide

# 🔍 Regular Expression (Regex) Reference & Pattern Guide

| Pattern Name | Regex Syntax | Flags | Example Match | Purpose |
|:---|:---|:---:|:---|:---|
| **Email Address** | `/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/i` | `i` | `user.dev@domain.com` | Standard RFC-compliant email validation |
| **URL / HTTP(S)** | `/^https?:\/\/(?:www\.)?[-a-zA-Z0-9@:%._+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b[-a-zA-Z0-9()@:%_+.~#?&/=]*$/i` | `i` | `https://markdownkite.com/docs` | Validates secure or insecure web URLs with optional paths |
| **UUID v4** | `/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i` | `i` | `f47ac10b-58cc-4372-a567-0e02b2c3d479` | Matches canonical 128-bit RFC 4122 version 4 UUIDs |
| **Semantic Version (SemVer)** | `/^v?(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$/` | `none` | `v2.14.0-rc.1` | Official SemVer 2.0.0 specification regex pattern |
| **IPv4 Address** | `/^(?:(?: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]?)$/` | `none` | `192.168.1.254` | Validates dotted quad IPv4 address within 0-255 octets |

## 💡 Common Character Classes Reference

| Token | Matches | Example |
|:---:|:---|:---|
| `\d` | Any digit (0-9) | `\d{3}` matches `123` |
| `\w` | Any alphanumeric word character or underscore | `\w+` matches `user_1` |
| `\s` | Any whitespace (space, tab, newline) | `\s+` matches multiple spaces |
| `^` / `$` | Start / End of input line | `^https://` asserts start with https |
| `(?:...)` | Non-capturing group | `(?:https|http)://` matches without capture |

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Complete Guide & Overview

Regular Expression (Regex) Reference & Pattern Documenter

Curate, document, and export regex patterns and token syntax into clean GitHub Flavored Markdown reference tables.

How to Use the Regular Expression (Regex) Reference & Pattern Documenter

Input Content

Paste or compose your markdown or source data into the input editor.

Customize Settings

Select formatting options, syntax modes, or display options.

Copy or Download

Copy the processed output to your clipboard or download the generated file.

Key Features & Capabilities

Structured pattern reference table showing regex syntax, flags, matched examples, and explanations.

Curated regular expression token cheat sheet for character classes, boundaries, and capture groups.

Presets for Web Validation, DevOps & System Logs, and Security Tokens.

Client-side processing ensuring strict privacy with zero data transmission.

Frequently Asked Questions

How does this tool help engineering teams document regex?

Complex regular expressions are notorious for being write-only and hard to maintain. This tool formats pattern syntax, flags, matched examples, and explanations into an intuitive GFM table with a character class cheat sheet for easy README onboarding.

What flags are supported?

Standard JavaScript and PCRE regex flags such as 'i' (case-insensitive), 'g' (global match), 'm' (multiline), and 's' (dotAll) are supported and displayed in dedicated table badges.

Are any patterns sent over the network?

No. All regex manipulation, markdown table assembly, and syntax validation execute entirely client-side in your browser. No strings or data leave your machine.

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