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Art Baker
Art Baker

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50 Regex Patterns Every Developer Should Have Bookmarked

#regex #python #javascript #webdev

Every time I need a regex, I end up Googling the same patterns. So I made myself a reference — here are 15 of the most useful from my full 50-pattern cookbook.

Each works across Python, JavaScript, Ruby, Go, and any PCRE engine.

Validation

Email (simplified RFC 5322) 

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

^https?://[^\s/$.?#].[^\s]*$
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Strong password (8+ chars, mixed case, digit, special) 

^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$
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UUID v4 

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

All URLs from text 

https?://[^\s<>"{}\\^`\[\]]+
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Email addresses from text 

\b[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}\b
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Currency amounts 

\$\d{1,3}(?:,\d{3})*(?:\.\d{2})?
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Version numbers (semver) 

\b\d+\.\d+\.\d+\b
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Cleaning

Strip HTML tags

Pattern: <[^>]+> — replace with empty string

Collapse multiple spaces

Pattern: \s+ — replace with single space

Mask credit card numbers

Pattern: \b(\d{4})\d{8}(\d{4})\b — replace with $1********$2

CamelCase to snake_case

Pattern: ([a-z0-9])([A-Z]) — replace with $1_$2, then lowercase

Log Parsing

Apache/Nginx log line 

^(\S+) \S+ \S+ \[([\w:/]+\s[+\-]\d{4})\] "(\S+) (.*?) (\S+)" (\d{3}) (\d+|-)
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Captures: IP, timestamp, method, path, protocol, status code, bytes

Python stack trace line 

File "([^"]+)", line (\d+), in (\w+)
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HTTP status code from log 

\s(2|3|4|5)\d{2}\s
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Using them in Python 

import re

# Compile once, reuse
EMAIL_RE = re.compile(r'\b[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}\b')
emails = EMAIL_RE.findall(text)

# Replace
cleaned = re.sub(r'<[^>]+>', '', html_text)

# Split on multiple delimiters
tokens = re.split(r'[,;\|\t]', messy_data)
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The full 50

These 15 are the ones I use most. The full cookbook has 50 patterns in 10 categories:

  • Validation (10) — email, URL, phone, IP, UUID, date, card, password, hex, slug
  • Extraction (10) — URLs, emails, hashtags, mentions, numbers, currency, HTML, markdown, code blocks, versions
  • Cleaning (10) — strip HTML, collapse whitespace, mask PII, CamelCase convert
  • Splitting (6) — CSV, multi-delimiter, camelCase, sentences, words
  • Log parsing (4) — Apache, Python, stack traces, HTTP status
  • File paths (5) — extensions, Windows, Unix, Docker, Git SHA
  • Advanced (5) — balanced parens, strings, JSON keys, SQL

Full cookbook: payhip.com/b/q8xTn ($9)

Also available:

What regex patterns do you reach for most?

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