How to Track Your Expenses with Claude (Using the Nexpenz MCP Server)

Most expense trackers are good at collecting data and bad at answering questions about it. You can see a pie chart of last month, but “Am I spending more on food than I was in the summer?” usually means tapping through filters, switching months and doing the maths yourself.

If you already use Claude, there’s a faster way: connect it to your expense tracker and just ask. This guide shows how to do that with Nexpenz and the Model Context Protocol (MCP), what you can ask once it’s set up, and what Claude can and can’t see.

This guide uses Claude, but the same setup works with ChatGPT, Cursor, Gemini CLI and any other MCP client. See the MCP setup guide for each one.

What is MCP, in plain terms?

The Model Context Protocol is an open standard that lets AI assistants like Claude connect to outside apps and services. An app publishes a set of “tools” (for example, “get spending by category for a date range”), and Claude calls them when your question needs that data.

Without MCP, Claude can only guess about your finances or work from numbers you paste in. With the Nexpenz MCP server connected, it looks up your actual transactions, budgets and bills at the moment you ask, so the answer is based on your real data instead of an estimate.

What you can ask Claude about your money

Nexpenz exposes 42 read-only tools covering every part of the app. You don’t need to know their names; Claude picks the right ones for each question. A few examples of what that looks like (the numbers below are illustrative):

Spending breakdowns

Budgets

Bills and subscriptions

Group splits

Other questions that work well:

• “Where did most of my money go last quarter?”
• “What were my 5 largest expenses this year?”
• “How much have I spent on coffee since January?”
• “How much is left on my car loan, and when will it be paid off?”
• “Compare my income and spending for the last 6 months.”

Because Claude can follow up, you can keep going in the same conversation: “Why was March so high?” or “Which of those could I cut?” That back-and-forth is where an AI assistant beats a static report.

How to connect Nexpenz to Claude

Setup takes under 5 minutes. You’ll need:

• A Nexpenz account on the Standard or Pro plan (MCP access isn’t included in the free plan).
• Claude Desktop or Claude Code.

Step 1: Create an API key in Nexpenz

In the Nexpenz app, go to Settings → MCP API Keys and create a key. Copy it straight away: it’s only shown once. If you plan to use Nexpenz from more than one device or client, create a separate key for each, so you can revoke one without affecting the others.

Step 2a: Claude Desktop

1. Open Claude Desktop and go to Settings → Developer → Edit Config. This opens claude_desktop_config.json.
2. Add Nexpenz under mcpServers, replacing YOUR_API_KEY with your key:

{
  "mcpServers": {
    "nexpenz": {
      "command": "npx",
      "args": [
        "mcp-remote",
        "https://mcp.nexpenz.com/mcp",
        "--header",
        "Authorization:Bearer YOUR_API_KEY"
      ]
    }
  }
}

3. Save the file, then fully quit Claude Desktop and reopen it. Closing the window isn’t enough.
4. Start a new chat. Nexpenz appears in the tools menu, and Claude asks for permission the first time it uses a tool.

Claude Desktop connects through mcp-remote, which is fetched automatically by npx. The only requirement is Node.js 18 or newer (run node -v in a terminal to check).

Step 2b: Claude Code

Run this in your terminal, replacing YOUR_API_KEY with your key:

claude mcp add --transport http nexpenz https://mcp.nexpenz.com/mcp \
  --header "Authorization: Bearer YOUR_API_KEY" --scope user

--scope user makes Nexpenz available in every project. Open a Claude Code session and run /mcp to confirm it shows as connected. Claude Code connects over HTTP directly, so there’s nothing else to install.

Using ChatGPT, Cursor or Gemini CLI instead? The MCP setup guide has step-by-step instructions for each.

Is it safe to connect my finances to Claude?

It’s the right question to ask before connecting anything to your money. Here’s how it works:

• Read-only. Every Nexpenz tool is read-only. Claude can look up and analyse your data, but it can’t add, edit or delete anything. Changes are only made in the Nexpenz app.
• Only your data. The key gives access to your own Nexpenz account and nothing else. Nexpenz doesn’t connect to your bank, so Claude never sees bank logins or card numbers.
• Fetched on demand. Data is only fetched when Claude calls a tool to answer a question. Nexpenz doesn’t store or log your AI conversations.
• Revoke anytime. Delete a key from Settings → MCP API Keys and access stops immediately.

One thing to be aware of: the results Claude fetches become part of your conversation, so they’re processed by Anthropic under Claude’s privacy terms, the same as anything else you type into a chat.

Troubleshooting

• Nexpenz doesn’t show up in Claude Desktop: check that the config file is valid JSON, the server URL is exactly https://mcp.nexpenz.com/mcp, Node.js 18+ is installed, and that you fully quit and reopened the app.
• Authentication error: make sure you replaced YOUR_API_KEY with your full key and kept the Bearer prefix. If it still fails, the key may have been revoked; create a new one.

Wrapping up

Tracking expenses only pays off if you actually look at the data. Connecting Nexpenz to Claude turns that into a conversation: ask a question, get an answer from your real numbers, and follow up. If you’re already using Claude every day, it’s the easiest way to keep an eye on your money without opening another dashboard.

New to Nexpenz? Start on the free plan to add your transactions, then upgrade to Standard or Pro when you’re ready to connect Claude.