io.github.rog0x/regex — MCP Server

This MCP server provides Regex test, explain, and replace capabilities for AI agents via the Model Context Protocol. It exposes tools to test patterns, perform replacements, extract matches, and explain patterns, all designed for integration with MCP-enabled agents and model contexts.

🛠️ Key Features

Tools: regex_test, regex_replace, regex_extract, regex_explain
Returns matches with indices, groups, and named captures
Supports capture group references in replacements
Structured extraction of matches as arrays
TypeScript-friendly interfaces for integration

🚀 Use Cases

Validate and debug regex patterns within MCP-driven workflows
Text processing: extraction and replacement in agent prompts
Explain and decompose complex patterns for model contexts
Prepare structured data for downstream MCP tools

⚡ Developer Benefits

Clear MCP tooling for regex and text processing
Rich match data: indices, groups, named groups
Consistent, explainable pattern analysis
Easy integration with TypeScript projects and MCP servers

⚠️ Limitations

Based on readme excerpt; ensure full tool docs for complete capabilities
Output formats depend on MCP implementation and tooling support

Tools

Tool

Description

regex_test

Test a regex pattern against text. Returns all matches with indices, captured groups, and named groups.

regex_replace

Find and replace using regex with support for capture group references ($1, $2, $&, $<name>).

regex_extract

Extract all matches of a pattern from text as a structured array. Optionally return only a specific capture group.

regex_explain

Parse a regex pattern and return a human-readable explanation of each component and flag.

text_transform

Apply common text transformations: camelCase, snake_case, kebab-case, PascalCase, UPPER, lower, title case, reverse, trim, deduplicate lines, sort lines, remove blank lines, count words/chars/lines. Chain multiple transforms in one call.

Usage with Claude Desktop

Add this to your Claude Desktop config file:

Windows: %APPDATA%\Claude\claude_desktop_config.json

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

json

{
  "mcpServers": {
    "regex-tools": {
      "command": "node",
      "args": ["D:/products/mcp-servers/mcp-regex-tools/dist/index.js"]
    }
  }
}

Examples

Test a regex

code

regex_test({ pattern: "(\\d{4})-(\\d{2})-(\\d{2})", text: "Today is 2026-03-19 and tomorrow is 2026-03-20" })

Replace with capture groups

code

regex_replace({ pattern: "(\\w+)\\s(\\w+)", replacement: "$2 $1", text: "hello world" })

Extract matches

code

regex_extract({ pattern: "[\\w.]+@[\\w.]+", text: "Contact us at info@example.com or support@example.com" })

Explain a regex

code

regex_explain({ pattern: "^(?:https?://)?(?:www\\.)?([\\w-]+)\\.\\w{2,}$", flags: "i" })

Transform text

code

text_transform({ text: "hello world example", transforms: ["PascalCase"] })
text_transform({ text: "some text\nwith\nlines\nwith\nduplicates\nlines", transforms: ["deduplicate_lines", "sort_lines"] })

io.github.rog0x/regex