regexANYvalidationuuid
regex
^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-5][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}$Covers UUID versions 1–5 and the standard variant bits.
Regex Examples and Cookbook
Large cookbook of validation, extraction, cleanup, and code-search regex recipes for everyday engineering work.
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Validation Recipes
Practical validators and shape checks.
regexANYvalidationipv4
regex
^(?:25[0-5]|2[0-4]\d|1?\d?\d)(?:\.(?:25[0-5]|2[0-4]\d|1?\d?\d)){3}$Avoids invalid octets like 999.
regexANYvalidationdomain
regex
^(?:[A-Za-z0-9](?:[A-Za-z0-9-]{0,61}[A-Za-z0-9])?\.)+[A-Za-z]{2,}$Good for a simple domain shape check.
regexANYvalidationcsscolor
regex
^#(?:[0-9A-Fa-f]{3}|[0-9A-Fa-f]{6}|[0-9A-Fa-f]{8})$Covers 3, 6, and 8 digit forms.
regexANYvalidationversions
regex
^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-[0-9A-Za-z.-]+)?(?:\+[0-9A-Za-z.-]+)?$Useful for package and release tooling.
regexANYvalidationdate
regex
^\d{4}-\d{2}-\d{2}$Shape validation only; calendar validity is a separate concern.
Extraction Recipes
Patterns that extract high-value substrings from larger text.
regexANYextractionurls
regex
https?://[^\s<>"']+A pragmatic extractor for logs, markdown, and prose.
regexANYextractionemail
regex
\b[^\s@]+@[^\s@]+\.[^\s@]+\bUseful for scanning text dumps and documents.
regexANYextractionmarkdown
regex
\[([^\]]+)\]\(([^)]+)\)Capture group 1 is the label and group 2 is the URL.
regexANYextractioncsv
regex
[^,]+Useful only for simple CSV; quoted CSV needs a more robust parser.
regexANYextractionmarkdowncode
regex
```(\w+)?
[\s\S]*?
```Common when cleaning or indexing markdown content.
regexANYextractionlogs
regex
\b(INFO|WARN|WARNING|ERROR|DEBUG|TRACE|FATAL)\bHelpful for log triage and indexing.
Cleanup and Normalization
Regexes that clean or normalize messy text.
regexANYcleanupline-endings
regex
\r
Useful when normalizing files to LF.
regexANYcleanupwhitespace
regex
(?:\r?
\s*){3,}Replace with `\n\n` or similar to reduce whitespace.
regexANYcleanupwhitespace
regex
^\s+|\s+$Use multiline mode to trim line edges.
regexANYcleanuphtml
regex
</?[^>]+>Okay for lightweight cleanup, not for full HTML parsing.
regexANYcleanupphone
regex
[-.\s()]Useful when converting formatted phone numbers into digits-only values.
regexANYcleanupsecurityredaction
regex
\b(?:\d{4}[- ]?){3}\d{4}\bUse carefully and sanitize logs responsibly.
Language and Data Format Recipes
Regex patterns used with source code and structured text.
regexANYjsonparsing
regex
"([^"\\]+)"\s*:Helpful for quick scans, though a parser is safer for full JSON.
regexANYyamlparsing
regex
^[A-Za-z0-9_.-]+:Useful for lightweight audits of YAML-like files.
regexANYsqllinting
regex
(?i)\bselect\s+\*\s+from\bUseful for database code cleanup.
regexANYhtmlattributes
regex
\bid=["\']([^"\']+)["\']Useful for audits and DOM refactors.
regexANYcssselectors
regex
\.[A-Za-z_-][A-Za-z0-9_-]*Useful for scanning stylesheets or extracting class tokens.
regexANYenvconfiguration
regex
^[A-Za-z_][A-Za-z0-9_]*=.*$Useful for scanning or validating env files.
More in Regex
Regex for VS Code and IDE Search
Regex patterns and search/replace recipes for VS Code, JetBrains IDEs, and common editor refactors.
Regex for PCRE, grep, ripgrep, and sed
Regex patterns and command-line workflows for grep, ripgrep, sed, awk, and advanced PCRE-style features.
Regex in JavaScript
JavaScript RegExp syntax, APIs, flags, named captures, and high-value browser/Node recipes.
Regex Cheat Sheet
Core regular expression syntax, classes, quantifiers, groups, lookarounds, flags, and performance techniques.