ChatGPT Obsidian MCP Proxy

A small local proxy that lets ChatGPT reach the Obsidian Local REST API MCP endpoint through a public HTTPS tunnel such as ngrok.

The proxy keeps your Obsidian API key on your machine. ChatGPT connects with No Auth, and this server adds the required Authorization: Bearer ... header before forwarding requests to Obsidian.

Architecture

flowchart LR
    A[ChatGPT App] -->|No Auth| B[ngrok HTTPS URL]
    B --> C[Local Proxy :3000]
    C -->|Authorization Bearer token| D[Obsidian Local REST API :27124]
    D --> E[(Obsidian Vault)]

Related MCP server: Obsidian Local REST API MCP Server

Requirements

• Obsidian

• Obsidian Local REST API community plugin

• Node.js LTS

• ngrok or another HTTPS tunnel

Setup

Install dependencies:

npm install

Create your local environment file:

Copy-Item .env.example .env

Edit .env and set:

OBSIDIAN_API_KEY=your_local_rest_api_key

Do not commit .env. It contains the secret token for your vault.

Run

Start Obsidian and confirm the Local REST API plugin is enabled.

Start the proxy:

npm start

Expected output:

Obsidian MCP proxy running on http://127.0.0.1:3000
Forwarding to https://127.0.0.1:27124

Test the proxy:

curl.exe http://127.0.0.1:3000/

The response should include:

"authenticated": true

Start ngrok:

ngrok http http://127.0.0.1:3000

Copy the HTTPS forwarding URL. Your ChatGPT MCP server URL is:

https://YOUR-NGROK-URL.ngrok-free.app/mcp/

Always include /mcp/ at the end.

ChatGPT App Configuration

Use these settings in ChatGPT Developer Mode:

Useful Checks

Test Obsidian directly:

curl.exe -k https://127.0.0.1:27124/

Test MCP through the proxy:

curl.exe http://127.0.0.1:3000/mcp/ -H "Accept: text/event-stream"

If the connection stays open or streams events, that is expected for MCP.

Security Notes

• Treat the ngrok URL like a temporary doorway into your vault.

• Do not share the ngrok URL.

• Stop ngrok when you are done.

• Stop this proxy when you are done.

• Never commit .env.

• Avoid exposing this permanently without stronger authentication.

Troubleshooting

See docs/runbook.md for the full setup runbook, validation flow, and common fixes.