List contacts and lists; create contacts, add them to lists and record events in Retainful. Hosted by usefulapi: connect it to Claude, ChatGPT, Cursor or any MCP client.
Turn on the Retainful connector, then ask in plain words. The AI picks the tools.
For ecommerce stores that send email and WhatsApp campaigns with Retainful.
List contacts one page at a time, with their consent status and source. Open one contact by its id to read its attributes.
List the lists and segments with their ids. Open one by id to read its details before you add contacts to it.
Create or update a contact by email and add it to a list in one call. Set the email consent only for people who really opted in. A list can start an automation.
Changes dataCreate a contact from a new sign-up, or update it when the email or phone already exists. Set the email consent explicitly. This does not add the contact to a list.
Changes dataRecord one event on a contact's timeline, such as a renewal with its amount. Automations that the event triggers can email the contact.
Changes dataThe login page asks for your Retainful API key.
Find it in Retainful → Integrations → your app → Create API key. Your key is used only to call the API on your behalf and to derive a private account id; it is never shown to anyone.
Team and Enterprise: an Owner adds the connector for the organization first.
No Add custom MCP server option? It depends on your account or workspace settings: see OpenAI's guide.
Run this command, then run /mcp in Claude Code to log in:
Add to Cursor or add this to ~/.cursor/mcp.json:
{
"mcpServers": {
"retainful": {
"url": "https://retainful.usefulapi.io/mcp"
}
}
} Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"retainful": {
"type": "http",
"url": "https://retainful.usefulapi.io/mcp"
}
}
} Run these commands. The second one opens the login page:
Windsurf, Cline, Zed and other MCP clients: add this URL as a remote MCP server (Streamable HTTP). The client then opens the login page in your browser.
Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Retainful API key. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
| Plan | Price | Limit |
|---|---|---|
| Free | $0 | 50 tool calls / month |
| Proper user | $9/mo · $90/yr | Unlimited* |
*Pro fair use limit: 10,000 tool calls a month on this server. For more, write to [email protected].
Pro covers this Retainful server only. Subscribe with retainful_upgrade (it returns a Stripe Checkout link). Cancel any time with retainful_cancel_subscription: Pro continues to the end of the paid period, with no refund for the current period, and running retainful_upgrade before then undoes the cancel. Or write to [email protected].
retainful_list_contactsretainful_get_contactretainful_list_listsretainful_get_listretainful_upsert_contactretainful_add_contact_to_listretainful_track_eventretainful_usage_statusretainful_request_featureretainful_upgraderetainful_cancel_subscriptionFind contacts and check their consent. Review the lists and segments. Add a new subscriber to a list. Create a contact from a new sign-up. Record a renewal event on a contact. See what you can do for the details.
No. usefulapi is an independent service. It is not affiliated with or endorsed by Retainful. The server calls the Retainful API with your own Retainful access, so it sees only the data that your account can see.
Yes. In Claude, add this server's URL as a custom connector. In ChatGPT, add it as a custom MCP server in Plugins. Then log in once. Cursor, VS Code, Claude Code and Codex work too. See the setup steps.
The login page asks for your Retainful API key. See Before you connect for where to find it.
No. Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Retainful API key. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
The login stores them encrypted in the authorization grant of your connection. The server uses them to call the Retainful API for you and to derive a private account id for usage metering. usefulapi does not show them on any page or in any reply. To stop all access, remove the connector and change or delete these credentials in Retainful.
Yes, if you approve it. 3 of the 7 Retainful tools can create or change data. The other 4 are marked read-only. Most MCP clients ask you to approve a tool call before it runs.
The Free plan gives 50 tool calls / month. Pro costs $9/mo or $90/yr, with unlimited tool calls (fair use limit: 10,000 tool calls a month), for this Retainful server only. Cancel any time: Pro then runs to the end of the paid period. Run retainful_usage_status to see how many calls you used.
Ask the AI to run retainful_upgrade: it returns a Stripe Checkout link. To cancel, run retainful_cancel_subscription. Pro continues to the end of the paid period.
Tell the AI what you wanted to do. It can send the request with retainful_request_feature. We store the text with the server name, the type of AI client and the tool you tried, not with your account, and read every request when we plan new tools. You can send up to 5 requests per day.
Any client that supports remote MCP servers (Streamable HTTP) with OAuth login: Claude (web and desktop), Claude Code, ChatGPT, Codex, Cursor, VS Code, Windsurf and others.
This is a Model Context Protocol endpoint — meant to be connected from an AI client, not opened in a browser. An invalid_token response at the URL is the auth gate working as designed; clients authenticate automatically.
Need a tool this server does not have, or a connection to another system? We build custom integrations and MCP servers.