Plaid MCP Server

A self-hosted MCP server for securely querying personal financial data through Plaid.

Connect an MCP-compatible AI assistant to bank accounts, balances, transactions, merchants, and spending data while keeping Plaid credentials and access tokens on your own server.

Overview

Plaid MCP Server exposes personal financial data through the Model Context Protocol (MCP), allowing an AI assistant to answer questions about connected bank accounts and transaction history.

The server handles authentication, Plaid account linking, financial-data retrieval, and MCP tool execution behind a self-hosted API.

Example queries:

"What did I spend on food last month?"

"Show me my largest purchases this week."

"How much have I spent at Trader Joe's this year?"

"What are my current account balances?"

Related MCP server: plaid-mcp

Available Tools

Architecture

┌──────────────────────┐
│  MCP Client / AI     │
└──────────┬───────────┘
           │ HTTPS + MCP
           ▼
┌──────────────────────┐
│        Caddy         │
│   TLS / Reverse Proxy│
└──────────┬───────────┘
           ▼
┌──────────────────────┐
│       FastAPI        │
│   MCP + OAuth Layer  │
└───────┬───────┬──────┘
        │       │
        │       └──────────────► Google OAuth
        │
        ▼
┌──────────────────────┐
│        Plaid         │
│ Accounts / Txns / PFC│
└──────────────────────┘

Authentication and Security

• OAuth 2.1 + PKCE with Google as the identity provider

• Email allowlist controls access to the server

• Plaid access tokens remain on the self-hosted server

• MCP clients receive a time-limited bearer token

• Caddy terminates TLS and reverse-proxies traffic to FastAPI

• HTTPS certificates are automatically provisioned through Let's Encrypt

Tech Stack

Backend: Python, FastAPI
Protocol: Model Context Protocol (MCP)
Financial data: Plaid API
Authentication: Google OAuth 2.1 + PKCE
Storage: SQLite
Infrastructure: AWS EC2, Caddy, systemd
Transport: HTTPS

Requirements

Before deploying, you'll need:

• A Linux server with a public IP

• A domain or subdomain pointing to the server

• A Plaid developer account with Production access

• A Google Cloud project with OAuth credentials

The setup below uses an AWS EC2 t3.micro instance and DuckDNS, but equivalent infrastructure should work as well.

Setup

1. Plaid

1. Create a Plaid developer account.

2. Request Production access through the Plaid dashboard.

3. Once approved, save your:

   • client_id

   • Production secret

2. Google OAuth

Create a Google Cloud project and configure an OAuth client.

Use the following redirect URI:

https://yourdomain.com/auth/google/callback

Save the generated:

• Client ID

• Client secret

3. Server

This example uses Ubuntu on AWS EC2.

1. Launch an Ubuntu 24.04 instance.

2. Allow inbound traffic on:

   • 22 for SSH

   • 80 for HTTP

   • 443 for HTTPS

3. Associate a stable public IP with the instance.

4. Connect over SSH.

ssh -i your-key.pem ubuntu@<server-ip>

4. Domain

Point a domain or subdomain at your server's public IP.

For a free option, DuckDNS works well:

plaid-yourname.duckdns.org

Then use:

https://plaid-yourname.duckdns.org/auth/google/callback

as the Google OAuth redirect URI.

5. Install

Clone the repository:

git clone https://github.com/lukew0824/plaid-mcp-server.git
cd plaid-mcp-server

Create your environment file:

cp .env.example .env
nano .env

Fill in the required values, then run:

./install.sh

The installer:

• Installs Python dependencies and Caddy

• Creates a systemd service

• Configures the application to restart automatically

• Configures Caddy as an HTTPS reverse proxy

6. Connect an MCP Client

For Claude.ai:

1. Open Settings → Connectors

2. Add a custom connector

3. Set the URL to:

https://yourdomain.com/mcp

4. Authenticate using the Google account configured in ALLOWED_EMAIL

5. Complete Plaid Link the first time you connect a financial institution

Once connected, the financial tools will be available to the MCP client.

Configuration

Project Structure

plaid-mcp-server/
├── app.py
├── crypto_utils.py
├── database.py
├── plaid_client.py
├── tools.py
├── install.sh
├── requirements.txt
├── .env.example
└── README.md

License

MIT