Why do I need developer mode?

Because a plain connector only gets the search and fetch tools. Developer mode is what lets ChatGPT call a full MCP tool set, which is what verification needs.

I am on a Business or Enterprise workspace and cannot see developer mode.

An owner or admin has to enable it first. On Business it is limited to owners and admins; on Enterprise and Education, admins can grant it to selected people and choose who can use each app.

Does this work in the ChatGPT mobile or desktop apps?

Developer-mode apps are a web flow. The desktop app and the Codex IDE extension read a local config file shared with the Codex CLI instead - the Codex CLI guide covers that path.

What does ChatGPT get access to?

Only the Qualisend workspace you approved, through the verification tools. It sees the verdict and score for an address, nothing about how the check runs and nothing from any other customer. Qualisend never receives your conversations or files.

ChatGPT (web)

by OpenAI

Verify email in ChatGPT

ChatGPT connects to remote MCP servers through developer mode. Turn it on, point a custom app at the Qualisend endpoint, and ChatGPT can verify addresses and clean lists in the conversation - with a real mailbox check behind every verdict.

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MCP endpoint: https://app.qualisend.com/api/mcp
Authentication: One-click sign-in
Available on: Plus, Pro, Business, Enterprise and Education, on the web only. On Business only owners and admins get developer mode, and each one turns it on for themselves - an admin cannot enable it for another member. On Enterprise and Education an admin grants access first, then each person turns it on in their own settings.

All clients

Claude
ChatGPT
Grok

Connect it to ChatGPT

You need a Qualisend account - the free plan includes 100 verification credits that never expire - and ChatGPT itself. Steps checked against OpenAI's documentation in September 2026.

1
Turn on developer mode
In ChatGPT on the web, go to Settings -> Security and login and switch Developer mode on. This is what unlocks full read and write MCP tools rather than search-only connectors.
2
Create the connection
Open chatgpt.com/plugins and click + to create a developer-mode app for a remote MCP server.
3
Paste the endpoint
Give it a name and description, then under Connection paste the endpoint - including the /api/mcp path. A bare domain will not resolve to the server.
```
https://app.qualisend.com/api/mcp
```
4
Choose OAuth and approve
Pick OAuth as the authentication mode and finish the sign-in. ChatGPT reads Qualisend's tool list and shows it for review; the app then lands under Drafts.
5
Select it in a conversation
Open the + menu in the composer, choose Developer mode, and select Qualisend for that chat. Prompting explicitly helps the first few times: "use Qualisend to verify this address".

One-click sign-in

Sign-in only. Pick OAuth when you create the connection and ChatGPT runs the approval flow for you. There is no field for pasting a Qualisend API key on this surface.

Check that it worked

Ask "how many Qualisend credits do I have left?". A number back means you are connected - that tool is free, so it costs nothing to test.

Worth knowing

The naming moved twice: connectors became apps, and a plugin is the newer wrapper that can bundle apps and skills. Older guides that say Settings -> Connectors are stale - the current route is Settings -> Security and login -> Developer mode, then chatgpt.com/plugins.
Paste the full URL with /api/mcp on the end. This is the single most common setup failure.
Write actions ask for approval by default, so expect a confirmation prompt the first time a verification runs.
After we ship new tools, open the app's details page and hit Refresh to re-pull the tool list. It does not update by itself.
This is web only. The ChatGPT desktop app uses a completely separate mechanism - see the Codex CLI guide, which shares its config file.

What to ask once it is connected

There are no commands to learn. Ask in your own words and ChatGPT picks the right tool - there are twelve, covering verification, sending-domain deliverability and blacklist checks.

“Verify sales@acme.com with Qualisend before I email them.”

“Use Qualisend to clean these 300 addresses and flag anything risky.”

“Are any of these signups disposable inboxes?”

“How many verification credits do I have left?”

What ChatGPT can reach

Only the verification tools, scoped to the single workspace you connect. It cannot reach another customer's data, your billing, or any admin function, and it never sees how a check is performed - just the verdict and the score. Authentication is an explicit token in a request header, never a cookie, so there is no session for a malicious page to borrow. Revoke it from ChatGPT or from your Qualisend dashboard at any time; sign-in access also expires on its own within an hour. Full detail is on the MCP documentation page.

ChatGPT FAQ

OpenAI's own reference: OpenAI's developer mode guide

Using something else?

It is the same endpoint everywhere. Pick your client:

Claude Grok Claude Code Cursor VS Code Codex CLI Gemini CLI Zed Goose Windsurf

Any other MCP-compatible client works too - Cline, JetBrains AI Assistant and the rest all take the same Streamable HTTP endpoint. The MCP documentation has the transport and authentication details.

Ready to connect ChatGPT?

Start free with 100 credits that never expire, then paste the endpoint.

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