PennyweightPennyweight

Connect another MCP client

Last updated October 9, 2026

On this page

Some AI apps don't have their own Pennyweight guide. They can connect if they meet three requirements. This page lists them and shows how to add Pennyweight. Start with Connect your AI and turn on two-factor first.

What your client needs

  • Remote MCP over HTTP. Pennyweight is a remote MCP server that uses the streamable HTTP transport. There is nothing to download or run on your computer. Your client only needs the URL.
  • OAuth sign-in. The client signs you in through Pennyweight with OAuth and a PKCE handshake. Pennyweight doesn't issue client IDs ahead of time. The client registers itself when it connects.
  • A supported callback. After you authorize, Pennyweight sends you back to the client. It only sends you back to a localhost address on your own computer, or to these web addresses: claude.ai, claude.com, chatgpt.com, chat.openai.com, openai.com, gemini.google.com, google.com, grok.com and x.ai.

Any other callback is refused, including app links such as myapp://. Pennyweight checks the callback when you authorize and again when the client collects its token.

How to do it

  1. In your client, find where it adds a remote MCP server or custom connector.
  2. Add a server named Pennyweight with this URL: . You can also copy it from Settings → Connect your AI in the web app.
  3. Choose OAuth (or "sign in") as the authentication method.
  4. When the client opens Pennyweight in your browser, sign in if asked, check the account it shows, enter your passphrase and click Authorize.
  5. Pennyweight sends you back to the client. Ask the check question below.

For Claude Code, follow Connect Pennyweight to Claude.

Example: Cursor

Per Cursor's docs, the Cursor desktop app signs in through a localhost callback (http://localhost:8787/callback). Pennyweight accepts that callback. It refuses the callback on cursor.com that Cursor's web app and Cursor Agents use.

Check the connection

Once you're connected, ask:

Try asking

Are you connected to Pennyweight? List my accounts.

What you'll see

Your AI calls Pennyweight and lists your accounts by name with their current balances. Next, try your first conversation.

Good to know

  • If the callback isn't supported, the authorization page says the connection isn't a recognized Pennyweight AI client and stops. Its message names Claude and ChatGPT, but Gemini, Grok and localhost callbacks are accepted too.
  • If the client skips the PKCE handshake or sends no callback, the page asks you to remove the Pennyweight server from your client and add it again.
  • Two-factor is required. If it's off, the page tells you to set it up in Settings → Security and retry. For other errors, see Can't authorize your AI.
  • Your AI never gets your passphrase or encryption keys. It gets an opaque token that lets Pennyweight's server decrypt your data for tool calls only.
  • The grant lasts 30 days of active use. Revoke it at any time from Settings → Connect your AI; see manage and revoke AI access.
  • 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.
  • Connect Pennyweight to ClaudeAdd Pennyweight as a custom connector in Claude on the web or desktop, or as a remote MCP server in Claude Code, then check the connection.