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Integrations

Stock market data
inside ChatGPT.

ChatGPT can call the OHLC MCP server as a developer-mode app, so you can ask for prices, dividends and financials in a conversation. If you only need help writing code against the API, give it the full reference instead.

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Remote MCP over HTTPS

ChatGPT connects to https://api.ohlc.io/mcp over streaming HTTP; nothing runs on your machine.

OAuth sign-in

OHLC supports OAuth with dynamic client registration, so ChatGPT signs you in without a client ID or secret.

Read-only tools

Every OHLC tool is annotated read-only, so ChatGPT does not treat any of them as a write action.

Docs for coding

/llms-full.txt gives ChatGPT the complete API contract and examples when you are writing an integration.

What ChatGPT supports today

As of October 2026, ChatGPT connects to custom remote MCP servers through developer mode, which OpenAI documents for Plus, Pro, Business, Enterprise and Education accounts on the web. It is not available on the free ChatGPT plan. OpenAI labels developer mode as elevated risk and intends it for people comfortable configuring and testing apps. On Business, Enterprise and Education workspaces an admin may need to allow it first. On the OHLC side you need a Developer plan or above, because MCP access is not part of the Free plan.

Add OHLC to ChatGPT

  1. In ChatGPT on the web, open Settings → Security and login and turn on Developer mode.
  2. Go to the ChatGPT apps page (chatgpt.com/plugins) and select the plus button to create a developer-mode app.
  3. Name it OHLC, enter https://api.ohlc.io/mcp as the server URL and choose OAuth authentication.
  4. Sign in to OHLC when prompted and approve access to your workspace. The app appears under Drafts in your app settings.
  5. In a conversation, choose Developer mode from the plus menu and select the OHLC app.

ChatGPT may reach for web browsing when it should call a tool. Naming the app and tool helps: “Use the OHLC app's get_eod_prices tool for XNAS:AAPL from 2026-09-01 to 2026-09-30. Do not browse the web.” OHLC's server instructions also tell the model which tool answers which question.

Example prompts

  • “Use OHLC to get the last 20 daily closes for XNAS:MSFT and compute the 10-day average.”
  • “With the OHLC app, list JNJ's dividends since 2021 with ex-dates and amounts.”
  • “Using OHLC, find the session's top percentage gainers on U.S. exchanges.”
  • “Ask the OHLC app's get_api_documentation tool how pagination works.”

Alternative: paste the API reference for coding help

If you want ChatGPT to write code rather than fetch data, you do not need MCP or developer mode. OHLC publishes LLM-ready documentation: /llms.txt is a compact index and /llms-full.txt is the complete reference, with every implemented operation, schemas and cURL, JavaScript and Python examples. It is large and may exceed smaller context windows; the LLM docs page lists smaller formats.

Starter promptText
Read https://ohlc.io/llms-full.txt and use its implemented OHLC API contract to build my integration. Choose the documented endpoints for my task, check required capabilities and coverage, and handle pagination, exact decimal strings, empty results and errors. Use OHLC_API_KEY from a server-side environment variable. Treat sample values as synthetic and never invent data availability.

Attach the file or let ChatGPT fetch the public URL, then describe what you are building. The files contain no credentials; keep your key in an environment variable rather than pasting it into the chat.

Limits, costs and troubleshooting

Tool calls from ChatGPT spend the same daily credits as REST requests and share your account's rate limits; the documentation tool is free. Prices are delayed at least 15 minutes or are end-of-day values, and the tools tell the model never to describe them as live.

  • New tools not showing: open the app's details page in ChatGPT's app settings and refresh it to pull the current tool list.
  • 403 from a tool: MCP needs an OHLC Developer plan or above, and some datasets, such as intraday bars, need Pro.
  • 429 from a tool: the account's rate or daily credit limit was reached; daily credits reset at 00:00 UTC.
  • To revoke ChatGPT's access, disconnect it from the MCP page of your OHLC account.

Questions, answered.

Can ChatGPT connect to a custom MCP server?

Yes, through developer mode, which OpenAI documents for Plus, Pro, Business, Enterprise and Education accounts on ChatGPT web as of October 2026.

Does it work on the free ChatGPT plan?

No. Custom MCP apps need developer mode, which the free ChatGPT plan does not include. You can still give ChatGPT /llms-full.txt for coding help.

Which OHLC plan do I need?

Developer or above for MCP. Your plan also decides which datasets ChatGPT can read; intraday bars need Pro.

Can ChatGPT change anything in my OHLC account?

No. Every OHLC MCP tool is read-only and returns market data or documentation.

Can I use an API key instead of OAuth in ChatGPT?

ChatGPT's developer mode supports OAuth, no authentication and mixed authentication. Use OAuth with OHLC; bearer-key configuration is for clients such as Claude Code.

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