Do I need a paid Claude plan?

No. Custom connectors are available on Free too, capped at one. Pro, Max, Team and Enterprise have no such cap. You also need a Qualisend account - the free plan includes 100 credits that never expire.

Can I paste a Qualisend API key instead of signing in?

Usually not. The dialog does have a Request headers section that can hold a static key, but it is in beta, only some organizations see it, and an admin sets one shared key for the whole organization. For everyone else the path is sign-in over OAuth 2.1, which is the safer one anyway: nothing to copy, nothing stored, and you can revoke it from the connector list. For a key per person, use Claude Code, Cursor, VS Code or another client that supports request headers.

What can Claude actually see?

Only the workspace you approved, and only through the verification tools. It gets the verdict for an address and its score - never how the check is performed, another customer's data, your billing, or any admin function. Qualisend never sees your conversations, files or memory either.

How do I disconnect it?

Remove the connector in Customize -> Connectors. Access tokens also expire on their own within an hour, and you can revoke everything from the Qualisend dashboard as well.

Claude (web, desktop and mobile)

by Anthropic

Verify email in Claude

Claude calls remote MCP servers as custom connectors. Add the Qualisend endpoint once and every conversation on your account - web, desktop and mobile - can verify addresses and clean lists with a real mailbox check behind each verdict.

Start free Full MCP documentation

MCP endpoint: https://app.qualisend.com/api/mcp
Authentication: One-click sign-in
Available on: Free (capped at one custom connector), Pro, Max, Team and Enterprise. On Team and Enterprise an Owner adds the connector for the organization first, then members connect their own account to it.

All clients

Claude
ChatGPT
Grok

Connect it to Claude

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

1
Open your connectors
Go to Customize -> Connectors on claude.ai, or straight to claude.ai/customize/connectors. The Claude desktop app shows the same list, because connectors live on your account rather than on the device.
2
Add a custom connector
Click the + next to Connectors and choose Add custom connector.
3
Name it and paste the endpoint
Call it Qualisend and paste the MCP endpoint. Leave Advanced settings empty - Qualisend registers Claude as a client automatically, so there is no client ID or secret to fill in.
```
https://app.qualisend.com/api/mcp
```
4
Approve the workspace
Click Add. Claude opens the Qualisend sign-in page; log in and approve the workspace you want it to use. The connection is limited to that one workspace.
5
Switch it on in a chat
In a conversation, click + -> Connectors and toggle Qualisend on. Then just ask in plain language.

One-click sign-in

Sign-in is the path here: Claude runs a one-click OAuth flow, so there is nothing to paste. Claude can also carry a fixed key through the Request headers section of the dialog, but that is in beta for a limited set of organizations and an admin sets one shared credential for everyone. If you do not see Request headers, or you want a key per person, use Claude Code or an editor client instead.

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

Claude reaches the server from Anthropic's cloud, not from your laptop. The endpoint has to be publicly reachable - app.qualisend.com is, but a localhost or VPN-only server would not work even in the desktop app.
Settings -> Extensions is a different thing. That is for local servers packaged as desktop extensions; a remote HTTPS endpoint belongs under Connectors.
On Team and Enterprise, members cannot add custom connectors themselves. An Owner adds it once under Organization settings -> Connectors (Add -> hover Custom -> Web); members then hit Connect on it under Customize -> Connectors.
Add it on claude.ai and it shows up in the desktop and mobile apps on its own. There is no need to repeat the setup per device.

What to ask once it is connected

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

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

“Clean this list of 200 signups and tell me which ones to drop.”

“Is hello@getresponse.io a role address or a real mailbox?”

“How many verification credits do I have left?”

What Claude 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 Claude 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.

Claude FAQ

Anthropic's own reference: Anthropic's custom connector guide

Using something else?

It is the same endpoint everywhere. Pick your client:

ChatGPT 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 Claude?

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

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