PennyweightPennyweight

Connect Pennyweight to ChatGPT

Last updated October 13, 2026

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You can add Pennyweight to ChatGPT as a custom MCP server, which ChatGPT lists as a plugin. Once it's connected, ask ChatGPT about your accounts and transactions in plain English. The steps below follow a real setup, screenshot by screenshot.

Before you start, read connect your AI for how the connection works, and turn on two-factor: Pennyweight requires it before it will authorize any AI.

Before you start

  • Use ChatGPT in a browser. You add the server from the Plugins page at chatgpt.com.
  • Your account has to allow it. OpenAI says account and workspace policies apply to adding and using custom MCP servers.

How to do it

1. Start a new plugin

Open Plugins (chatgpt.com/plugins) and click the + button at the top right. If a menu opens, choose Add custom MCP server.

ChatGPT's Plugins page. A plus button sits at the top right of the page, next to the Search plugins field, marked with an arrow.
The Plugins page. The + button, top right, starts a new plugin.

2. Fill in the plugin details

ChatGPT opens a New Plugin dialog. Fill it in like this:

  • Icon: optional. Skip it.
  • Name: Pennyweight.
  • Description: optional. "Pennyweight personal finance" is enough.
  • Connection: leave it on Server URL (not Tunnel) and paste . This is the same URL every Pennyweight user pastes.
  • Authentication: choose OAuth. You don't need Advanced OAuth settings: Pennyweight publishes the sign-in details ChatGPT looks for, so ChatGPT finds them itself.
  • Tick I understand and want to continue. ChatGPT shows this warning because OpenAI hasn't reviewed the server.
  • Click Create. OpenAI's guide calls this button Create as a plugin.
ChatGPT's New Plugin dialog filled in: Name 'Pennyweight', Description 'Pennyweight personal finance', Connection set to Server URL with https://mcp.pennyweight.ai, Authentication set to OAuth, and the 'I understand and want to continue' checkbox ticked.
The completed New Plugin dialog, with the risk notice acknowledged.

3. Sign in with Pennyweight

ChatGPT shows an Add Pennyweight to ChatGPT panel. Click Sign in with Pennyweight. If you aren't signed in to Pennyweight in this browser, sign in first; you come back to the next page.

ChatGPT's 'Add Pennyweight to ChatGPT' panel, with a 'Sign in with Pennyweight' button and notes about permissions and connector risk.
Click Sign in with Pennyweight to start the handshake.

4. Authorize on Pennyweight

You land on Pennyweight's Connect Pennyweight to your AI page. It shows the account being connected and the client ID, and says your AI client wants to read and write your Pennyweight ledger. Enter your passphrase and click Authorize. Pennyweight sends you back to ChatGPT.

Pennyweight's authorize page, headed 'Connect Pennyweight to your AI'. It shows the account and client ID (redacted here), a passphrase field, and Authorize and Cancel buttons.
Pennyweight's authorize page. The account and client ID are redacted in this screenshot; yours will show your own.

If this page shows an error instead, see can't authorize your AI.

5. Check it connected

Back on the Plugins page, open Pennyweight. Your account appears under Connected accounts. Permissions can stay on the default, Allow low-risk tools.

The Tools section may say "No app tools available yet" even when the connection works. Don't treat it as a failure. The real test is the next step.

Pennyweight's plugin settings in ChatGPT, showing a connected account (redacted), Permissions set to 'Allow low-risk tools', and a Tools section reading 'No app tools available yet'.
Connected. The 'No app tools available yet' line under Tools is misleading — the tools are there.

6. Ask it something

Start a new chat, type @, choose Pennyweight, and ask:

Try asking

Are you connected to Pennyweight? List my accounts.

What you'll see

ChatGPT calls Pennyweight and replies with your accounts by name, with balances. If you have more than one ledger, accounts from each appear, except demo ledgers. When a demo ledger is your active ledger, you see only its accounts. That reply means the connection works end to end. See your first conversation with Pennyweight.

Good to know

  • Reading vs. changing data. If ChatGPT answers questions but won't save a change, see ChatGPT won't add or change data.
  • New Pennyweight features. When you create the plugin, ChatGPT shows the tools it discovered from the server. If something new doesn't show up later, open Pennyweight on the Plugins page and select Refresh, then start a new chat.
  • How long access lasts. The grant lasts 30 days of active use. Pennyweight never gives ChatGPT your passphrase or encryption keys.
  • Removing access. Revoke ChatGPT any time from Settings → Connect your AI in Pennyweight. See manage AI access.
  • Other AIs. The same server works with Claude and other supported clients.
  • Connect your AIAdd Pennyweight to Claude, ChatGPT, Gemini or Grok with one link, then authorize it with your passphrase. How connecting works and where each guide lives.
  • Turn on two-factor authentication (and why it's required)Turn on two-factor in Settings before you connect a bank or authorize your AI. Here is where to find it and what changes if you turn it off.
  • Can't authorize your AIThe Pennyweight page that approves your AI stopped you with a message. Here is what each message means and how to get the connection through.
  • ChatGPT won't add or change dataChatGPT reads your Pennyweight data but doesn't save a change. Why it asks for approval first, and what else stops a write.