Regex Linter

Detect error-prone and risky regex patterns, check for catastrophic backtracking, unanchored patterns, and provide rewrite suggestions

## Regex Linter ## Overview Regex Linter analyzes regular expressions for common anti-patterns, performance issues, and correctness problems. It helps you write better, safer, and more efficient regular expressions. ## Issues Detected ### Critical Issues (Performance) - **Catastrophic Backtracking**: Nested quantifiers like `(a+)+` that can cause exponential time complexity - **Quadratic Behavior**: Patterns like `(.*)*` that exhibit O(n²) performance - **Unbounded Repeats**: Greedy quantifiers without maximum length limits ### Error Issues (Correctness) - **Unescaped Dots**: Using `. ` when you mean \. (literal dot) - **Missing Anchors**: Patterns that can match anywhere in the text - **Invalid Character Classes**: Ranges like `[a-Z]` that include unexpected characters - **Octal Escapes**: Ambiguous `` escapes in modern regex ### Warning Issues (Readability) - **Observable Non-Greedy**: `.*?` patterns that could use negated character classes - **Redundant Escapes**: Unnecessary backslashes like `\-` - **Double Negation**: Confusing `[^[^]]` patterns - **Ambiguous Alternation**: `a|ab` where order matters ### Info Issues (Style) - **Non-Capturing Groups**: Suggesting `(?:...)` when groups aren't referenced - **Verbose Patterns**: Can simplify `ddd` to `d{3}` ## Check Levels - **basic**: Only critical performance issues - **standard**: Critical + errors + warnings (recommended) - **strict**: All issues including style suggestions ## Dialect Support - **JavaScript**: ES2018+ features including lookbehind and Unicode property escapes - **Python**: Recommends raw strings, supports verbose regex option - **PCRE**: Warns about backtracking verbs if used unintentionally - **Go (RE2)**: Warns about unsupported features (lookbehind, backreferences) - **Java**: Version-specific feature warnings ## Example Input: ```regex (.*+)a ``` Output: ```json { "summary": { "score": 50, "severity": "error", "issuesFound": 2 }, "issues": [ { "severity": "critical", "message": "Catastrophic backtracking risk", "suggestion": { "pattern": "[^a]*a", "explanation": "Use negated character class instead" } } ] } ```

API Documentation

Request Endpoint

POST /en/api/tools/regex-linter

Request Parameters

Parameter Name	Type	Required	Description
regexPattern	text	Yes	-
regexFlags	text	No	-
targetDialect	select	No	-
checkLevel	select	No	-
includeSuggestions	checkbox	No	-

Response Format

{
  "key": {...},
  "metadata": {
    "key": "value"
  },
  "error": "Error message (optional)",
  "message": "Notification message (optional)"
}

JSON Data: JSON Data

AI MCP Documentation

Add this tool to your MCP server configuration:

{
  "mcpServers": {
    "elysiatools-regex-linter": {
      "name": "regex-linter",
      "description": "Detect error-prone and risky regex patterns, check for catastrophic backtracking, unanchored patterns, and provide rewrite suggestions",
      "baseUrl": "https://elysiatools.com/mcp/sse?toolId=regex-linter",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

You can chain multiple tools, e.g.: `https://elysiatools.com/mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp`, max 20 tools.

If you encounter any issues, please contact us at [email protected]