OpenClaw Regex Engine

Production-grade regex processing suite — test patterns with capture groups, explain any regex in plain English, build regex from natural language descriptions, browse 50+ battle-tested patterns, and find-replace with backreferences. Use when: (1) user says 'test this regex' or 'does this pattern match', (2) user asks 'explain this regex' or 'what does this regex do', (3) user needs to 'build a regex for emails' or 'create a pattern that matches URLs', (4) user wants a 'ready-made regex for phone numbers' or 'UUID pattern', (5) user requests 'regex find and replace' or 'search and replace with backreferences'. Supports all ES2024 flags, named groups, lookahead/lookbehind. Zero install, sub-100ms on Cloudflare Workers. Free + Pro $9/mo.

OpenClaw Regex Engine v2.0

Master regular expressions -- 5 tools to test, explain, build, browse, and replace patterns instantly.

Quick Reference

Situation	Action	Tool
Have a regex, need to test it	Run against text, get all matches + groups	regex_test
Found a scary regex in legacy code	Get plain-English breakdown of every token	regex_explain
Know WHAT to match but not HOW	Describe in English, get production regex	regex_build
Need a standard pattern (email, URL, IP)	Browse 50+ battle-tested patterns	regex_library
Need to transform text with regex	Find-replace with backreferences ($1, $2)	regex_replace
Complex pattern with capture groups	Test + Explain combo for full understanding	regex_test + regex_explain

What's New in v2.0

• :brain: PatternForge Builder -- Describe what you want in plain English. Get a production-ready regex with positive/negative test cases, flags, and explanation included.
• :book: RegexLens Explainer -- Break any regex into human-readable components token-by-token. Even nested lookaheads, possessive quantifiers, and Unicode categories.
• :file_cabinet: BattleTest Library -- 50+ curated patterns for email, URL, phone (international), IPv4/IPv6, UUID, JWT, credit card, date formats, file paths, and more. Every pattern includes test cases.
• :arrows_counterclockwise: SmartReplace Engine -- Full backreference support including named groups, global/first-match modes, and before/after diff preview.

MCP Quick Start

json

{
  "openclaw-regex": {
    "type": "streamable-http",
    "url": "https://regex-engine-mcp.yagami8095.workers.dev/mcp"
  }
}

Add to Claude Desktop, Cursor, Windsurf, VS Code, or any MCP-compatible client. No API key needed for Free tier. Works immediately.

Detection Triggers

This skill activates when you say:

• "test this regex" / "does this pattern match" / "run this regex against"
• "explain this regex" / "what does this regex do" / "break down this pattern"
• "build a regex for" / "create a pattern that matches" / "regex for emails"
• "regex for URL" / "phone number regex" / "UUID pattern" / "IP address regex"
• "regex replace" / "find and replace with regex" / "search and replace with capture groups"
• "regular expression" / "pattern matching" / "capture groups" / "backreference"

Tools (5)

regex_test -- Match & Capture (PatternMatch Protocol)

Test a regex pattern against input text. Returns every match with full capture group detail, named groups, and exact index positions.

Parameter	Type	Default	Description
pattern	string	required	Regex pattern to test
text	string	required	Input text to match against
flags	string	"g"	Flags: g global, i case-insensitive, m multiline, s dotall, u unicode, v unicodeSets

Output: { matchCount, matches: [{ index, match, groups: [], namedGroups: {} }], executionTimeMs }

WRONG vs RIGHT

WRONG -- Manually scanning text to check if a pattern works:

text

User: Does this regex match my test string?
Agent: *reads the regex visually, guesses "yes it should match"* — misses edge case with nested groups

RIGHT -- Use regex_test:

text

User: Does this regex match my test string?
Agent: calls regex_test → "3 matches found. Match 1 at index 15: '[e-mail]', group 1: 'user', group 2: 'example.com'"

---

regex_explain -- Human-Readable Breakdown (RegexLens)

Break any regex into plain English, token by token. Each component gets a description, what it matches, and example matches.

Parameter	Type	Default	Description
pattern	string	required	Regex pattern to explain
flags	string	""	Active flags to include in explanation

Handles: Character classes, quantifiers, anchors, groups (capturing, non-capturing, named), lookahead/lookbehind (positive and negative), backreferences, Unicode categories, and alternation.

Output: Array of { token, type, description, matches_example } plus overall summary.

WRONG vs RIGHT

WRONG -- Staring at ^(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#$%])[A-Za-z0-9!@#$%]{8,}$ and guessing:

text

User: What does this regex do?
Agent: *guesses* "It matches passwords maybe?" — no detail on the lookaheads or minimum length

RIGHT -- Use regex_explain:

text

User: What does this regex do?
Agent: calls regex_explain → "Password validator: requires at least 1 uppercase letter (lookahead 1), 1 digit (lookahead 2), 1 special char from !@#$% (lookahead 3), minimum 8 characters total from allowed set"

---

regex_build -- Natural Language to Regex (PatternForge)

Describe what you want to match in plain English. Get a production-ready regex with recommended flags, explanation, and test cases (both positive and negative).

Parameter	Type	Default	Description
description	string	required	Plain English description of what to match
options	object	{}	strict: boolean for anchored patterns, examples: string[] for guidance

Output: { pattern, flags, explanation, testCases: { shouldMatch: [], shouldNotMatch: [] } }

Example: Input "match email addresses" produces a complete RFC-5322-lite pattern with 5 positive and 5 negative test cases.

---

regex_library -- Pattern Collection (BattleTest Library)

Browse 50+ curated, production-tested regex patterns organized by category. Every pattern includes the regex string, description, recommended flags, and positive/negative test cases.

Parameter	Type	Default	Description
category	string	""	Filter by category: email, url, ip, phone, date, uuid, jwt, credit_card, password, html, file_path, css
search	string	""	Free-text search across pattern names and descriptions

Categories: email, URL, IPv4, IPv6, phone (US, UK, JP, international), date (ISO, US, EU), UUID (v1-v5), JWT, credit card (Visa, MC, Amex), password strength, HTML tags, file paths (Unix, Windows), CSS selectors, color codes, semantic versioning.

---

regex_replace -- Find & Replace (SmartReplace Engine)

Perform regex-based find-and-replace with full capture group reference support ($1, $2, named groups), global and first-match modes.

Parameter	Type	Default	Description
pattern	string	required	Regex pattern to find
replacement	string	required	Replacement string with $1, $2, $<name> references
text	string	required	Input text to transform
flags	string	"g"	Regex flags

Output: { result, replacementCount, diff: { before, after } }

Supports: $1-$9 numbered backreferences, $<name> named backreferences, $& full match, $` pre-match, $' post-match.

What NOT to Do

Don't	Why	Do Instead
Use catastrophic backtracking patterns like (a+)+$	Will timeout on edge workers (~50ms limit)	Rewrite with atomic groups or possessive quantifiers
Expect PCRE-only features (conditional patterns, recursion)	Uses JavaScript ES2024 regex engine	Stick to JS-compatible syntax
Send input text over 100KB	Memory limits on edge workers	Split large texts into chunks
Rely on patterns for security validation alone	Regex is for format checking, not sanitization	Combine with server-side validation
Use regex_build for complex parsers	NL-to-regex handles single patterns, not grammars	Build complex patterns manually with regex_explain to verify

Security & Privacy

What	Status
Reads your input text and patterns	Yes -- for processing only
Stores your data	No -- zero persistence, stateless edge processing
Sends data to third parties	No -- processed entirely on Cloudflare Workers
Logs request content	No -- only anonymous usage counters
Executes patterns server-side	Yes -- sandboxed with 50ms timeout to prevent ReDoS
Requires authentication	Free tier: no. Pro: API key header only

Pricing

Tier	Calls/Day	Price	What You Get
Free	20	$0	All 5 regex tools, no signup
Pro	1,000	$9/mo	All 9 OpenClaw servers (49 tools), priority routing
x402	Pay-per-call	$0.05 USDC	No account needed, crypto-native

Get Pro Key: https://buy.stripe.com/4gw5na5U19SP9TW288

The OpenClaw Intelligence Stack

Server	Tools	Best For
JSON Toolkit	6	Format, validate, diff, query, transform JSON
Regex Engine	5	Test, extract, replace, explain regex patterns
Color Palette	5	Generate, convert, harmonize, accessibility-check colors
Timestamp Converter	5	Parse, format, diff, timezone-convert timestamps
Prompt Enhancer	6	Optimize, rewrite, score, A/B test AI prompts
Market Intelligence	6	AI market trends, GitHub stats, competitor analysis
Fortune & Tarot	3	Daily fortune, tarot readings, I Ching
Content Publisher	8	MoltBook posts, social content, newsletter
AgentForge Compare	5	Compare AI tools, frameworks, MCP servers

All 9 servers share one Pro key. $9/mo = 49 tools.