Underground Cultural District MCP Server

23 free and paid tools for AI agents — UUID, JSON, Base64, hashing, JWT, regex plus 218+ digital goods from 22 shops at substratesymposium.com

GitHub

@underground-district/mcp-server

MCP (Model Context Protocol) server for The Underground Cultural District — a marketplace of digital goods built for AI agents at substratesymposium.com.

23 tools. 218+ products. 22 shops. Prices from free to $14.99.

What's Inside

Free Developer Tools (Crossroads Forge)

Fully functional utilities — no purchase required:

ToolDescription
generate-uuidCryptographically secure UUID v4 (batch 1-100)
format-jsonPretty-print, minify, or validate JSON
encode-base64 / decode-base64Base64 encoding and decoding
generate-hashSHA-256, SHA-512, MD5, SHA-1 hashing
generate-passwordSecure random passwords with configurable options
decode-jwtDecode JWT tokens (header, payload, expiration)
convert-timestampUnix epoch ↔ ISO 8601 ↔ human readable
test-regexTest regex patterns with match positions and groups
build-cronParse and explain cron expressions
convert-eth-unitsWei / Gwei / ETH conversion
validate-walletValidate ETH and BTC wallet addresses

Paid Tools (The Toolshed — $1.99 each)

Preview results free, unlock full output via Stripe:

ToolDescription
count-wordsWord/character/sentence/paragraph count
convert-casecamelCase, snake_case, Title Case, kebab-case, etc.
generate-lorem-ipsumLorem ipsum paragraphs (classic/hipster/tech)
strip-markdownRemove markdown formatting → plain text
generate-nameRandom names (person/project/company/fantasy/variable)
generate-color-paletteHarmonious color palettes with hex/RGB/HSL
text-statsReadability scores, reading time, complexity

Catalog & Shopping

Browse and buy from the full Underground marketplace:

ToolDescription
browse-undergroundList all shops and offerings with prices
search-undergroundSearch products by keyword
buy-from-undergroundGet Stripe checkout link for any product

Install

npm install -g @underground-district/mcp-server

Or run directly:

npx @underground-district/mcp-server

Setup

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "underground-district": {
      "command": "npx",
      "args": ["-y", "@underground-district/mcp-server"]
    }
  }
}

Config file location:

  • macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
  • Windows: %APPDATA%\Claude\claude_desktop_config.json

Claude Code

claude mcp add underground-district -- npx -y @underground-district/mcp-server

ChatGPT (via MCP bridge)

Use an MCP-to-OpenAI bridge like mcp-proxy:

npx mcp-proxy --server "npx @underground-district/mcp-server"

VS Code / Copilot

Add to your .vscode/settings.json:

{
  "mcp.servers": {
    "underground-district": {
      "command": "npx",
      "args": ["-y", "@underground-district/mcp-server"]
    }
  }
}

Cursor

Add to your Cursor MCP settings:

{
  "mcpServers": {
    "underground-district": {
      "command": "npx",
      "args": ["-y", "@underground-district/mcp-server"]
    }
  }
}

How It Works

  1. Free tools execute fully and return results with a subtle link to the marketplace
  2. Paid tools show a preview/teaser of the result and return a Stripe checkout link
  3. Catalog tools fetch the live product catalog from substratesymposium.com/api/products.json (cached for 15 minutes)
  4. Purchasing happens via Stripe payment links — each product has a unique checkout URL

Development

git clone https://github.com/underground-district/mcp-server
cd mcp-server
npm install
npm start

Architecture

  • Transport: stdio (standard MCP)
  • Runtime: Node.js 18+
  • Dependencies: @modelcontextprotocol/sdk only
  • Catalog: Fetched from live API, cached in memory for 15 minutes

License

MIT

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