@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:

Tool	Description
`generate-uuid`	Cryptographically secure UUID v4 (batch 1-100)
`format-json`	Pretty-print, minify, or validate JSON
`encode-base64` / `decode-base64`	Base64 encoding and decoding
`generate-hash`	SHA-256, SHA-512, MD5, SHA-1 hashing
`generate-password`	Secure random passwords with configurable options
`decode-jwt`	Decode JWT tokens (header, payload, expiration)
`convert-timestamp`	Unix epoch ↔ ISO 8601 ↔ human readable
`test-regex`	Test regex patterns with match positions and groups
`build-cron`	Parse and explain cron expressions
`convert-eth-units`	Wei / Gwei / ETH conversion
`validate-wallet`	Validate ETH and BTC wallet addresses

Paid Tools (The Toolshed — $1.99 each)

Preview results free, unlock full output via Stripe:

Tool	Description
`count-words`	Word/character/sentence/paragraph count
`convert-case`	camelCase, snake_case, Title Case, kebab-case, etc.
`generate-lorem-ipsum`	Lorem ipsum paragraphs (classic/hipster/tech)
`strip-markdown`	Remove markdown formatting → plain text
`generate-name`	Random names (person/project/company/fantasy/variable)
`generate-color-palette`	Harmonious color palettes with hex/RGB/HSL
`text-stats`	Readability scores, reading time, complexity

Catalog & Shopping

Browse and buy from the full Underground marketplace:

Tool	Description
`browse-underground`	List all shops and offerings with prices
`search-underground`	Search products by keyword
`buy-from-underground`	Get 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

Free tools execute fully and return results with a subtle link to the marketplace
Paid tools show a preview/teaser of the result and return a Stripe checkout link
Catalog tools fetch the live product catalog from substratesymposium.com/api/products.json (cached for 15 minutes)
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

The Underground Cultural District MCP Server