plaid-mcp

A self-hosted MCP server that lets Claude query your bank accounts, balances, and transactions through Plaid.

Tools

How it works

• OAuth 2.1 + PKCE with Google as the identity provider

• Email allowlist is the security boundary

• Claude.ai gets a 30-day bearer token; your Plaid access token never leaves your server

• Caddy sits in front of FastAPI, terminating TLS on port 443 with auto-provisioned Let's Encrypt certs and reverse-proxying to localhost:8080

Requirements

• A Linux server with a public IP (this guide uses an AWS EC2 t3.micro)

• A domain name pointing at it (this guide uses a free DuckDNS subdomain)

• A Plaid developer account with production access

• A Google Cloud account for the OAuth client

Setup

1. Plaid

1. Create a Plaid account at dashboard.plaid.com

2. Request Production access in the dashboard (Plaid will review your application — this can take a few days)

3. Once approved, save your client_id and Production secret from Team Settings → Keys

2. Google OAuth

1. console.cloud.google.com → create a project

2. APIs & Services → OAuth consent screen → set up an "External" app, add yourself as a test user

3. APIs & Services → Credentials → Create credentials → OAuth client ID

4. Application type: Web application

5. Authorized redirect URIs: https://yourdomain.com/auth/google/callback (use your real domain from step 4 below)

6. Save the Client ID and Client secret

3. Server

This guide assumes AWS EC2:

1. Launch a t3.micro Ubuntu 24.04 instance

2. Security group: inbound TCP 22 (SSH from your IP), 80, 443

3. Allocate an Elastic IP and associate it with the instance

4. SSH in: ssh -i your-key.pem ubuntu@<elastic-ip>

4. Domain

Free option using DuckDNS:

1. Sign in with Google/GitHub/Reddit

2. Reserve a subdomain (e.g. plaid-yourname)

3. Set the IP to your Elastic IP

4. Your domain is now plaid-yourname.duckdns.org

Go back to step 2.5 and set the redirect URI to https://plaid-yourname.duckdns.org/auth/google/callback.

5. Install

On the server:

git clone https://github.com/lukew0824/plaid-mcp.git
cd plaid-mcp
cp .env.example .env
nano .env   # fill in everything
./install.sh

The script:

• Installs Python, Caddy, and dependencies

• Sets up a systemd service (plaid-mcp)

• Configures Caddy as a reverse proxy with auto-HTTPS via Let's Encrypt

6. Connect in Claude.ai

1. Claude.ai → Settings → Connectors → Add custom connector

2. URL: https://yourdomain.com/mcp

3. Click Connect

4. Sign in with the Google account matching ALLOWED_EMAIL

5. First time only: a Plaid Link popup will appear — connect your bank

6. Done. Try: "What did I spend on food last month?"

Configuration

The .env values:

License

MIT