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

{
  "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:

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.

| 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:

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).

| 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, $ references |

| text | string | required | Input text to transform |

| flags | string | "g" | Regex flags |

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

Supports: $1-$9 numbered backreferences, $ 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.