io.github.rog0x/regex MCP Server

This Model Context Protocol (MCP) server provides regex and text processing tools for AI agents. It supports testing patterns against text, performing regex-based replacements, extracting matches, and generating explanations for regex patterns.

🛠️ Key Features

Tools for regex testing, replacement, extraction, and explanation
Regex testing returns matches with indices, captured groups, and named groups
Regex replacement supports capture-group references ($1, $2, $&, $<name>)
Extraction can return structured arrays and optionally a specific capture group

🚀 Use Cases

Validate regex patterns on sample text before use
Apply standardized transformations via regex replacement
Pull specific entities or fields from text using capture groups
Produce human-readable breakdowns of regex patterns for agent workflows

⚡ Developer Benefits

Structured match outputs (indices, captured groups, named groups)
Capture-group reference support for deterministic replacements
Extraction produces structured arrays for downstream processing

⚠️ Limitations

The available documentation excerpt truncates the regex_explain tool details after “returns a”.

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