Openclaw Regex Engine

OpenClaw Regex Engine v2.0

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

Quick Reference

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

{
  "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.

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

WRONG vs RIGHT

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

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:

User: Does this regex match my test string?
Agent: calls regex_test → "3 matches found. Match 1 at index 15: 'user@example.com', 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.

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:

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

RIGHT -- Use regex_explain:

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).

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.

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.

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

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

What NOT to Do

Security & Privacy

Pricing

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

The OpenClaw Intelligence Stack

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