Polyglot DB

Polyglot DB MCP lets you query and manage many databases through a single, natural-language interface. Built with ReScript and running on Deno, it supports PostgreSQL, Redis, Elasticsearch, Neo4j, MongoDB, and many more—so you can perform cross-database tasks without juggling multiple CLIs or query languages.

How to use

You connect to the MCP server from your MCP client and issue natural-language requests that span multiple databases. For example, you can ask the system to find users in PostgreSQL who signed up last week and check if they’re present in the Redis cache, or search Elasticsearch logs and correlate with a MongoDB audit log. The MCP server handles dispatching the right actions to each database adapter and returns unified results.

How to install

Prerequisites: you need a working Node.js environment for building components and Deno for running the server in development scenarios.

# Option A: Direct (Recommended for development)
# Clone the repository
git clone https://github.com/hyperpolymath/polyglot-db-mcp.git
cd polyglot-db-mcp

# Start the MCP server in development mode (example command from development flow)
den o task start

# Option B: Container (Recommended for production)
# Using nerdctl (containerd)
nerdctl run -d --name polyglot-db \
  -e POSTGRES_HOST=host.docker.internal \
  -e MONGODB_URL=mongodb://host.docker.internal:27017 \
  ghcr.io/hyperpolymath/polyglot-db-mcp:latest

# Using podman
podman run -d --name polyglot-db \
  -e POSTGRES_HOST=host.containers.internal \
  ghcr.io/hyperpolymath/polyglot-db-mcp:latest

# Using docker
docker run -d --name polyglot-db \
  -e POSTGRES_HOST=host.docker.internal \
  ghcr.io/hyperpolymath/polyglot-db-mcp:latest

# Option C: Deno Deploy (Serverless / HTTP Mode)
# Deploy to Deno Deploy
deployctl deploy --project=polyglot-db-mcp server.js

# Or run HTTP mode locally
deno task serve

# Then configure your MCP client to connect via HTTP (example)
{
  "mcpServers": {
    "polyglot-db": {
      "transport": {
        "type": "http",
        "url": "https://polyglot-db-mcp.deno.dev/mcp"
      }
    }
  }
}

Additional configuration and notes

Configure each database you want to use by providing environment variables. You only need to set the variables for the databases you enable. The server reads its configuration from environment variables for each adapter.

# PostgreSQL
POSTGRES_HOST=localhost
POSTGRES_PORT=5432
POSTGRES_DATABASE=mydb
POSTGRES_USER=postgres
POSTGRES_PASSWORD=secret

# Redis (Dragonfly)
DRAGONFLY_HOST=localhost
DRAGONFLY_PORT=6379
DRAGONFLY_PASSWORD=

# Elasticsearch
ELASTICSEARCH_URL=http://localhost:9200
ELASTICSEARCH_USERNAME=elastic
ELASTICSEARCH_PASSWORD=secret

Usage examples for tools and queries

Common workflows include listing connected databases, checking connection status, and querying specific databases by sending natural-language prompts to Claude (or other MCP clients). You can ask about connected databases, fetch a table schema, or perform a cross-database operation like caching a query result.

# Meta tools (examples)
db_list

db_status

db_help postgres

Available tools

db_list

List all supported databases connected to the MCP server.

db_status

Check which databases are currently connected.

db_help

Get available tools for a specific database.