ChatGPT File Store — MCP Server

A Model Context Protocol server that lets ChatGPT (or any MCP client) save and manage files inside a sandboxed local folder on your Mac.

Everything ChatGPT does is confined to an allowed directory — it cannot read or write anywhere else on your machine.

What it does

ChatGPT gets these tools:

Tool	Purpose
list_allowed_directories	Shows where ChatGPT is allowed to save/read
list_directory	Lists files and folders in the store
read_file	Reads a text file
get_file_info	File metadata (size, modified time)
search_files	Finds files matching a pattern (*.md, *notes*)
write_file	Saves a file (creates folders automatically)
append_file	Appends to a running log/notes file
create_directory	Creates folders
move_file	Moves/renames files
delete_file	Deletes a file or folder

Folder layout

mcp-chatgpt-file-store/
├── src/
│   ├── index.ts        # entrypoint — stdio or HTTP mode
│   ├── http.ts         # Streamable HTTP server (stateful sessions)
│   ├── server.ts       # MCP server + tool registration
│   └── filesystem.ts   # sandboxed file operations + path safety
├── chatgpt/            # default sandbox — <folder where server runs>/chatgpt
└── package.json

Two ways to run it

The server supports two transports — pick whichever your client wants:

Mode	Command	Endpoint
stdio (default)	npm run start	n/a (local process)
Streamable HTTP	npm run start:http	http://localhost:3000/mcp

Setup

1. Install dependencies and build

cd mcp-chatgpt-file-store
npm install
npm run build

2. Choose where ChatGPT can save

By default the sandbox is <folder where the server runs>/chatgpt (i.e. the chatgpt/ folder inside this project). To use your own folder(s), set an environment variable:

export CHATGPT_FILE_STORE_DIRS="/path/to/my/notes,/path/to/another"

3. Test it locally (optional but recommended)

npm run inspect

This opens the MCP Inspector where you can call each tool before wiring it to ChatGPT.

4a. Connect over stdio

In ChatGPT, add a custom MCP server with this command:

node /absolute/path/to/mcp-chatgpt-file-store/dist/index.js

Tip: point the command at the built dist/index.js (not src), and use the absolute path. If you set CHATGPT_FILE_STORE_DIRS, make sure that environment variable is visible to the process ChatGPT launches.

4b. Connect over Streamable HTTP

Start the HTTP server (default port 3000):

npm run start:http

Or with a custom port/host:

node dist/index.js --http --port 8080 --host 0.0.0.0
# or via environment variables
MCP_HTTP_PORT=8080 MCP_HTTP=1 node dist/index.js

Via the npm script, pass flags after --:

npm run start:http -- --port 8080 --host 0.0.0.0

Then register http://localhost:3000/mcp as the MCP server URL in ChatGPT.

Authentication (recommended for any non-localhost deployment)

Set MCP_AUTH_TOKEN to require a Bearer token on every /mcp request:

MCP_AUTH_TOKEN=$(openssl rand -hex 32) node dist/index.js --http --port 8080

Requests must then include Authorization: Bearer <token> — otherwise they get a 401 Unauthorized. /health stays open (no token needed) for liveness checks. When registering the connector in ChatGPT, add the same value as a custom header: Authorization: Bearer <token>.

If MCP_AUTH_TOKEN is not set, the server logs a startup warning and accepts unauthenticated requests — fine for quick local testing, not for anything reachable from the internet. The server implements the MCP Streamable HTTP transport:

• POST /mcp — JSON-RPC requests (first call creates a session and returns a Mcp-Session-Id header; send it back on subsequent requests)
• GET /mcp — SSE stream for server-initiated messages
• DELETE /mcp — ends a session
• GET /health — liveness check ({"status":"ok","sessions":N})

Example usage

Once connected, you can tell ChatGPT things like:

• "Save the summary of our conversation to notes/summary.md"
• "Append today's ideas to ideas.md"
• "List everything in the projects folder"
• "Search for files containing draft in the name"

Security notes

• Every path is resolved and checked against the allowed roots before any operation.
• .. traversal and paths outside the roots are rejected with an error.
• In stdio mode the server exposes no network port at all.
• In HTTP mode the server binds to 0.0.0.0:3000 by default — use --host 127.0.0.1 to restrict it to localhost only. Sessions are tracked by random UUID. Set MCP_AUTH_TOKEN (see Authentication above) before exposing this server beyond localhost — without it, anyone who finds the URL can read/write files in the sandbox.
• Only the configured directory is readable/writable — treat the sandbox as not secret (ChatGPT content is processed by the model provider).

Commands

npm run build      # compile TypeScript
npm run start      # run compiled server over stdio
npm run start:http # run compiled server over Streamable HTTP (port 3000)
npm run dev        # run stdio mode with tsx (no build step)
npm run dev:http   # run HTTP mode with tsx (no build step)
npm run inspect    # open MCP Inspector UI