CHATGPT

Connect ChatGPT
with OAuth.

Add Mermail as a custom OAuth app in an eligible ChatGPT workspace.

Why ChatGPT

Built for the agent you already use.

Mermail gives ChatGPT a dedicated inbox and payment layer so verification, checkout, and receipts stay in the same loop.

Custom MCP app on ChatGPT web

OAuth 2.1 through console.mermail.app

No x-api-key in ChatGPT settings

Explicit Business / Enterprise prerequisites

Before you start

Check 3 things.

ChatGPT web: Business or Enterprise/Edu.

Developer mode and admin/developer access.

Access to the intended Mermail workspace.

ChatGPT MCP docs

Success contract

Done when all 3 pass.

Mermail is enabled in a new chat.

Mermail tools appear in the picker.

list_mailboxes succeeds.

Three steps to connect.

Copy the Mermail MCP URL

Use Streamable HTTP and OAuth. Add no headers.

MCP endpoint

https://console.mermail.app/mcp

Add a custom MCP connector

Open Settings → Apps → Create. Paste the URL, choose OAuth, then scan tools.

Open ChatGPT Apps

Connect, authorize, then verify

Finish OAuth, enable Mermail in a new chat, then run the check.

Verify

Ask: "List my Mermail mailboxes" (tool: list_mailboxes)

Do I need an API key in ChatGPT?

No. Choose OAuth and add no headers.

Why do I not see Create under Apps?

Use ChatGPT web. Ask an admin to enable Developer mode and grant app-creation access.

Why can ChatGPT not see my Codex MCP?

ChatGPT web does not read local Codex config. Add Mermail in ChatGPT Apps.

See all integrations

Integration index

Claude Code

Connect OAuth and install 15 skills for inbox, verification, and x402 workflows.

Codex

Connect OAuth and install 15 skills for inbox and x402 workflows.

Cursor

Add the hosted MCP server with OAuth—no API key required.

Grok

Connect Mermail to Grok web chat and Grok Bot with OAuth, PayBox, and inline MCP Apps.

OpenClaw

Connect with OAuth, then verify Mermail with a live probe.

Hermes

Add Mermail to Hermes with Streamable HTTP OAuth.

Connect ChatGPTwith OAuth.