How to Connect Walnut to ChatGPT, Step by Step
Last updated November 2026
Short answer
Turn on Developer Mode in ChatGPT's settings, add the Walnut MCP server as a custom connector, sign in with your Walnut account and approve. The URL is https://walnutinvest.com/api/connector/mcp. The one practical catch is ChatGPT's own: custom connectors need a paid plan with Developer Mode, which is OpenAI's requirement. Access is read-only, your broker login never leaves your broker, and ChatGPT cannot place orders through it. Walnut is not an investment adviser.
ChatGPT is the assistant most people already have open, and it is the one most likely to answer a question about your portfolio using a portfolio it has invented from your description. Connecting it fixes the input. The reasoning was usually fine; it was being applied to the wrong holdings at the wrong prices.
Step 1. Turn on Developer Mode
Custom MCP connectors sit behind Developer Mode in ChatGPT's settings, and it requires a paid plan. People most often get stuck here, so know before you start that the gate is OpenAI's and has nothing to do with Walnut.
ChatGPT moves its settings around, so any exact menu path would soon be wrong. Look under settings for a developer or advanced section, and for the area that manages apps or connectors. If you cannot find it, your plan may not include it.
Step 2. Add the connector and sign in
Add a new custom connector with the Walnut server URL:
https://walnutinvest.com/api/connector/mcp
ChatGPT will open a sign-in for your Walnut account. Approve the access request and the connector is live. You are never asked for a brokerage username or password at any point, and you should never provide one to an assistant that asks.
If you have not connected a broker inside Walnut yet, do that first. The connector can only surface what Walnut can see.
Step 3. Check it worked
Ask something only a connected assistant could answer: “what are my five largest holdings and what are they worth right now?” Real positions with current values means it is working. A general answer, or a request that you paste your holdings, means the connector is not enabled for that conversation.
What ChatGPT can see once connected
| What | Detail |
|---|---|
| Your positions | Every holding in the account you connect, with share counts and current value |
| Live prices | Fetched when you ask, never recalled from training data |
| Performance | Each holding and the whole portfolio against the S&P 500 |
| Drift | How far each position sits from the target weight you set |
| Rebalance math | What trades would return a portfolio to target, described for you to review |
| Your portfolios | The thematic portfolios built in Walnut and their stated reasoning |
| Order history | Orders placed through Walnut, including any still pending at the broker |
| Connected brokers | Which accounts are linked, and whether each is read-only or trade-enabled |
Connected versus pasted, concretely
Pasting holdings into a chat is the obvious free alternative outside the US (US users can also link accounts read-only through Finances in ChatGPT), and the differences matter because the failure modes are quiet:
| Pasted into chat | Connected | |
|---|---|---|
| What you own | Whatever you remembered to type | Read from the connected account |
| Prices | May come from training data, stated confidently | Fetched at the time you ask |
| Positions you forgot | Silently missing from the analysis | Included, because the list is not from memory |
| Next week | You retype everything | Nothing to redo |
The third row is the one that causes real trouble. An analysis that silently omits a position you forgot will still sound complete, and concentration is exactly the thing you would have wanted it to catch. More on that in what ChatGPT Finances can and can't see.
Get a recommendation for your situation
Walnut is the AI that knows your portfolio: ask anything in plain English, research any fund, and get an honest second opinion. On the broker you already use, read-only, and you approve every trade. Walnut is not a registered investment adviser.
Read-only, and how to revoke it
The connector reads holdings and does not place orders. There is no setting that changes that. Trading through Walnut happens in Walnut's own assistant on the web, where an order is previewed, stated plainly as spending real money, and confirmed by you before anything is placed.
To revoke, remove the connector in ChatGPT's settings, which stops that client. To cut access at the source, disconnect the broker inside Walnut, which revokes it regardless of which assistant is asking. See is it safe to connect your brokerage to an AI.
If it does not work
You cannot find Developer Mode. The most likely reason is your plan. Custom connectors are a paid feature and the setting is hidden entirely on plans that do not include it, so it looks like a missing menu item, with no sign that it is locked.
ChatGPT answers generally despite the connector being added. Connectors usually need to be active in the specific conversation, not just installed. Start a fresh chat with the connector enabled before concluding anything is broken.
It returns an empty portfolio. Walnut can only surface what it can see, so this nearly always means no broker is connected in Walnut or the connection needs reauthorising. Check inside Walnut first.
The sign-in does not stick. Confirm you are signing in to the Walnut account that holds the broker connection. Having created a second account by accident is a more common cause than anything technical.
What this does not do
It does not give advice. ChatGPT with the connector attached can tell you what you hold, how it has done against the market, and where you are concentrated. Describing a portfolio and recommending what to do about it are different things, and Walnut is not an investment adviser.
It does not see anything outside the accounts you connect, so a spouse's portfolio, a pension or a business are invisible to it. That matters because the combined picture is where most genuine concentration problems live, and a confident answer about one account can be wrong about the whole.
And it does not know your tax position, so anything it says about selling is arithmetic, not tax planning. Where that boundary sits is worked through in what free portfolio analysis can and cannot do.
If ChatGPT is not the right client for you
The Developer Mode and paid-plan requirement is a genuine obstacle for some people, and the same connector URL works elsewhere. Claude supports custom connectors on its own terms, including in Claude Code from the terminal. Codex and Cursor also accept remote MCP servers.
For a neutral survey of every route, beyond the Walnut setup, connecting a brokerage to ChatGPT compares the approaches, and the connect hub covers the whole picture.
FAQ
I cannot find Developer Mode in ChatGPT. Why?
Most likely your plan. Custom connectors are a paid feature and the setting is hidden entirely on plans that do not include it, so it looks like a missing menu item, with no sign that it is locked. If you would rather not pay for that, the same connector URL works in Claude on its own terms.
Does the connector see accounts I have not connected?
No. It reads only the brokerage accounts you have linked in Walnut. A spouse's portfolio, a pension or a business are invisible to it, which matters because the combined household picture is where most genuine concentration problems live.
Can ChatGPT tell me what to buy once connected?
It can describe what you hold, how it has performed and where you are concentrated. Telling you what to buy would be advice, and Walnut is not an investment adviser. It also does not know your tax position, so anything it says about selling is arithmetic, not tax planning.
How do I connect Walnut to ChatGPT?
Turn on Developer Mode in ChatGPT's settings, then add the Walnut MCP server as a custom connector and sign in with your Walnut account. The server URL is https://walnutinvest.com/api/connector/mcp. There is nothing to download and no API key to generate. Custom connectors in ChatGPT require a paid plan with Developer Mode enabled.
Why does ChatGPT need Developer Mode?
Custom MCP connectors are gated behind it, which is OpenAI's choice and nothing specific to Walnut. It is a setting you enable once, and it is the practical difference between connecting a portfolio to ChatGPT and to Claude, where custom connectors are available without a separate mode.
Do I need a paid ChatGPT plan?
For custom connectors, yes at the time of writing. That requirement comes from OpenAI and changes independently of anything on our side, so check the current plan requirements in ChatGPT's own settings. If you would rather not pay for it, Claude supports custom connectors on its own terms and the same server URL works there.
What is the Walnut MCP server URL?
https://walnutinvest.com/api/connector/mcp. Add it as a custom connector, sign in with your Walnut account, and approve access. The same URL works in every client that supports remote MCP servers, so you can add it in more than one assistant.
Does ChatGPT get my broker password?
No. Your broker login stays with your broker. Walnut connects through a secure connection and never sees or stores those credentials, and ChatGPT authenticates to Walnut using your Walnut account. It never signs in to your broker. No assistant is ever given a brokerage password.
Can ChatGPT place trades through the connector?
No. The connector is read-only for holdings. It analyzes, compares and can draft a portfolio for you to review, and it does not place orders. Trading through Walnut happens in Walnut's own assistant on the web, with a preview and an explicit confirmation for every order.
Why not just paste my holdings into ChatGPT?
You can, and it fails in three predictable ways: it is stale the moment prices move, it silently omits anything you forgot, and ChatGPT may fill price gaps from training data with complete confidence. A connector reads the current account and fetches current prices each time, so none of those apply.
Doesn't ChatGPT Finances already show my portfolio?
In the US, it can. Finances in ChatGPT links accounts through Plaid on every plan and shows investments, current value and position size, with no connector needed. It is US-only, it cannot trade, and it has no target weights. Walnut adds thematic portfolios with target weights, scores each holding against the S&P 500, works in Claude as well, and handles trades you approve in Walnut's own assistant.
Will ChatGPT remember my portfolio between chats?
It does not need to. The connector is re-read whenever you ask, so a new conversation starts with current holdings. A connection reads the account fresh each time, while a memory would keep whatever was true last time, so the answers do not drift out of date.
How do I revoke access?
Remove the connector in ChatGPT's settings, which stops that client immediately. To revoke at the source, disconnect the broker inside Walnut, which cuts the underlying data access regardless of which assistant is asking.
Can I use the same connector in ChatGPT and Claude at once?
Yes. The same server URL can be added in several clients, and each authenticates separately with your Walnut account. Many people keep it in both and use whichever assistant they happen to be in.
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Walnut is informational and is not an investment adviser, and nothing here is investment advice. ChatGPT's plan requirements and settings layout are set by OpenAI and change; check the current requirements in ChatGPT's own settings. The connector URL above is current.