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Connect to Claude

Ask about any US public company and get the real numbers back — revenue, margins, segments, a decade of history. Your assistant stops hallucinating figures and answers from live, verified data, grounded in what each company actually reported. So you can dig into a business, size it up against peers, and move fast on what you find — with every number traceable to where it came from.

Claude, by Anthropic, supports the Model Context Protocol (MCP), which lets it connect directly to OpenCapital. Here's how to set it up in a couple of minutes.

How to connect

Add the OpenCapital connector

Follow the steps below to add OpenCapital in Claude. It works the same on Claude web and desktop.

Open Connectors

Click the "Customize" button in the top left of Claude, then select "Connectors".

Open settings

Click "Add custom connector"

Click the "+" button in the top right of the Connectors panel, then select "Add custom connector".

Paste your URL and name it

In the "Add custom connector" dialog, enter "OpenCapital" as the name and paste your MCP server URL. Then click "Add".

https://api.opencapital.sh/mcp

Click "Connect" and authorize

Find OpenCapital in the connectors list and click "Connect". Claude opens an OpenCapital sign-in window — sign in and click Authorize to grant read-only access. Claude then verifies the server and establishes the connection.

Now just ask.

Open a chat and ask about any company — Claude answers with real numbers from OpenCapital, not guesses.

Start a chat

Try asking

Works with Claude Desktop and Claude.ai

Same steps on Claude Desktop and Claude.ai with MCP enabled. Data is read live, so Claude always sees the latest.

Read-only by design

Exposes read-only research data from public SEC filings. Claude cannot place trades or change any account.

Troubleshooting

My AI doesn't see OpenCapital's tools

Make sure the connector is added, enabled, and signed in. Still nothing? Ask it to “use the OpenCapitalMCP server” — in ChatGPT, start the message with @OpenCapital.

The sign-in window didn't open

Authorization opens in your browser — allow pop-ups and retry. In Claude Code run /mcp → Authenticate; in the Codex CLI, run codex mcp login opencapital.

It says “needs login” or stopped working

Tokens can expire — re-authorize from your client's connector settings, or remove and re-add the OpenCapital server.

Connection failed or the server is unreachable

Confirm the URL is exactly https://api.opencapital.sh/mcp, the transport is Streamable HTTP (not stdio), and your client is up to date.

Still stuck?

Email support@opencapital.sh and we'll help you get connected.

Disclosures

Informational only — not investment advice

OpenCapital provides financial data and research, not recommendations. Nothing here is an offer or personalized investment, legal, or tax advice — do your own research.

Data sources and accuracy

Derived automatically from public SEC filings and other sources; it may contain errors or delays and is provided “as is.” Verify against primary sources — see our methodology.

Read-only access

The OpenCapital MCP server is read-only — it cannot place trades, move money, or modify any account.

Third-party AI clients

Your prompts and the data returned are processed by your AI client (Claude, ChatGPT, Codex, Cursor) under its own terms. AI can be wrong — verify before acting.

Authorization

Connecting grants read access via OAuth; revoke it anytime from your client's settings. Use is governed by our Terms and Privacy Policy.