Connect an AI assistant to PiggySize

PiggySize is a standard MCP server, so you can connect an AI assistant — Claude, ChatGPT, or any other assistant that supports custom connectors — to your PiggySize account and then ask it about your own numbers: what you owe, what a bill costs you a year, how your net worth has moved. When you connect, you choose whether the assistant may only look at your data or may also change it. Everything happens through an approval screen you see in your own browser, and you can cut the connection off at any time from Settings (opens in a new tab) on the Connected Apps tab.

Before you start

• You need a PiggySize account and an account with the assistant you want to connect. Any PiggySize plan works, and so does any role — owner, spouse, or child.
• The connection is scoped to whoever is signed in when it is approved. A child account's connection reaches only that child's data.
• If you use two-factor authentication, have your authenticator app handy — you are asked to confirm a code before the connection is approved.

The address you paste in

Whichever assistant you use, you paste one of these two addresses:

• https://piggysize.com/api/mcp — you choose read-only or read & write when you approve it.
• https://piggysize.com/api/mcp/readonly — a connection that can never change anything.

The generic steps (any MCP client)

Because PiggySize is a standard MCP server, the setup is the same everywhere. Wherever your assistant keeps its connector or MCP settings:

1. Add a custom or remote MCP connector and point it at the address above.
2. A PiggySize window opens. Sign in if you are not already signed in.
3. On the approval screen, pick Read-only or Read & write, then choose Approve.

The finished connection shows up under Settings (opens in a new tab) on the Connected Apps tab.

The rest of this article is just where each popular assistant hides that flow.

Claude

This is the path we test end to end.

1. Open Settings in Claude, then Connectors.
2. Choose Add custom connector.
3. Paste the address and choose Connect.
4. Sign in to PiggySize if asked, pick the access level, and choose Approve.

What you can add and how much you can use it depends on your Claude plan.

ChatGPT

ChatGPT supports custom MCP connectors through Developer mode, on the web app for its paid tiers.

1. In ChatGPT, turn on Developer mode (in Settings, under Apps → Advanced).
2. Add a custom connector and paste the address.
3. Complete the OAuth sign-in to PiggySize, then pick the access level and approve.

One honest caveat: ChatGPT's Deep Research feature expects a connector to expose its own search and fetch tools, so PiggySize's finance tools may not show up in every ChatGPT feature. ChatGPT also warns that custom connectors are not reviewed by OpenAI — the read-only address is there if you want a connection that structurally cannot change anything.

Claude Code

Run this in your terminal:

claude mcp add --transport http piggysize https://piggysize.com/api/mcp

Claude Code opens the same PiggySize approval screen in your browser. Sign in if needed, pick the access level, and choose Approve.

Other clients

Cursor, VS Code with GitHub Copilot, Windsurf, and other MCP clients connect the same way — add the server address in the app's MCP settings (for example, Cursor's Tools & MCP settings, or a type: "http" server in VS Code's mcp.json) and complete the browser sign-in. There is nothing client-specific about the server, and the list grows as more assistants adopt the protocol.

Choosing an access level

The approval screen offers up to two choices, and it always names which one you are granting:

• Read-only — "View your profile and financial data. It cannot change anything." The assistant can look at your overview, bills, income, assets, debts, goals, businesses, scenarios, net worth history, and profile.
• Read & write — everything above, plus adding, editing, and deleting bills, income, assets, and debts.

If the assistant only asked for read access, read-only is the only option and the screen says so. You can also connect to https://piggysize.com/api/mcp/readonly instead, which offers no write tools at all.

Whatever you pick is shown as a badge next to the connection on the Connected Apps tab, so you can see at a glance which connections can change things.

Disconnecting

1. Go to Settings (opens in a new tab) and open the Connected Apps tab.
2. Find the connection and choose Revoke.
3. Confirm. Access stops immediately and the connection disappears from the list.

Connect again the same way whenever you want it back.

Good to know

• A connection never gives an assistant more than your own account has. The same permissions that govern what you see in the app govern every request the connector makes, so a child account reaches only its own data and a family member with limited access stays limited.
• PiggySize records which tool was used, when, and whether it worked. The values read or written are not recorded, and neither is your conversation — that stays with your assistant.
• Nothing about a connection changes your PiggySize login. Revoking a connection does not sign you out, and changing your password does not disconnect a connected app — revoke it on the Connected Apps tab.

If it isn't working

• The Connected Apps tab isn't there, or the assistant can't reach PiggySize. The connector can be switched off for the whole site, and support can switch it off for a single account. If you expected it and it isn't there, contact us (opens in a new tab).
• You get sent to a login page and back again. Approval happens in the browser, so you must be able to sign in to PiggySize in that same browser window. Sign in there first, then start the connection again.
• The approval screen asks for a code. That is two-factor authentication doing its job. Enter the code from your authenticator app, or one of your backup codes.

FAQ

Which assistants can I connect? Any MCP-capable assistant. Claude is the fully-tested path. ChatGPT works too (turn on Developer mode first). Claude Code, Cursor, VS Code with GitHub Copilot and others connect the same way.

Which address do I paste in? https://piggysize.com/api/mcp (opens in a new tab) — or https://piggysize.com/api/mcp/readonly (opens in a new tab) if you want a connection that can never change anything.

Do I need Pro? No. The connector works on every PiggySize plan, for the account owner, a spouse, and a child account. Some assistants need their own paid tier to add custom connectors.

Can the assistant change my data? Only if you pick Read & write on the approval screen. Read-only connections can look at your data and nothing else.

How do I disconnect? Open Settings, go to the Connected Apps tab, and choose Revoke next to the connection. Access stops immediately.

What can a child account reach through the connector? Only what that child account can already see in PiggySize. A connection never widens what an account is allowed to reach.

What does PiggySize record about what the assistant does? Which tool was used, when, and whether it succeeded — never the values that were read or written, and never your conversation.