Query people, segments, campaigns, and message deliveries; send transactional email or broadcasts. Hosted by usefulapi: connect it to Claude, ChatGPT, Cursor or any MCP client.
Turn on the Customer.io connector, then ask in plain words. The AI picks the tools.
For marketers and growth teams who message customers with Customer.io.
The AI reads a campaign and its delivery and engagement metrics over time. It sums up how the campaign did.
The AI finds a person with an attribute filter, then lists their attributes, the segments they belong to and the messages sent to them. You see what this customer got.
The AI lists all segments and then searches people with a segment or attribute filter. You get the people who match.
The AI lists sent messages filtered by type, campaign or newsletter. You can check what went out and compare campaigns.
The AI sends one transactional email from a template to a recipient, or triggers an API-triggered broadcast. This sends real messages.
Changes dataThe login page asks for your Customer.io App API key and Workspace region.
Find your key in Customer.io → Account Settings → API Credentials → App API Keys. 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": {
"customerio": {
"url": "https://customerio.usefulapi.io/mcp"
}
}
} Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"customerio": {
"type": "http",
"url": "https://customerio.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 Customer.io App API key and Workspace region. 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 |
| Pro | $9/mo · $90/yr | 10,000 tool calls / month |
| Pro+ | $39/mo · $390/yr | 100,000 tool calls / month |
Each paid plan covers this Customer.io server only. Ask your AI to run customerio_upgrade and choose Pro or Pro+, billed monthly or yearly (it returns a Stripe Checkout link). If you already have Pro, ask to change it to Pro+. The change requires your confirmation, keeps your billing interval and charges the price difference for the rest of the period immediately. Cancel any time with customerio_cancel_subscription: your paid plan continues to the end of the paid period, with no refund for the current period, and asking to resume the same plan with customerio_upgrade before then undoes the cancel. Or write to [email protected].
customerio_search_customerscustomerio_get_customer_attributescustomerio_get_customer_segmentscustomerio_get_customer_messagescustomerio_list_segmentscustomerio_list_campaignscustomerio_get_campaigncustomerio_get_campaign_metricscustomerio_list_messagescustomerio_list_exportscustomerio_list_collectionscustomerio_send_transactional_emailcustomerio_trigger_broadcastcustomerio_usage_statuscustomerio_request_featurecustomerio_upgradecustomerio_cancel_subscriptionCheck how a campaign performed. See what a person received. List the people in a segment. Review recent deliveries across the workspace. Send a transactional email or trigger a broadcast. See what you can do for the details.
No. usefulapi is an independent service. It is not affiliated with or endorsed by Customer.io. The server calls the Customer.io API with your own Customer.io 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 Customer.io App API key and Workspace region. See Before you connect for where to find them.
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 Customer.io App API key and Workspace region. 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 Customer.io 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 Customer.io.
Yes, if you approve it. 2 of the 13 Customer.io tools can create or change data. The other 11 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 10,000 tool calls / month. Pro+ costs $39/mo or $390/yr, with 100,000 tool calls / month. Each subscription covers this Customer.io server only. Cancel any time: your paid plan then runs to the end of the paid period. Run customerio_usage_status to see how many calls you used.
Ask the AI to run customerio_upgrade and choose Pro or Pro+, billed monthly or yearly: it returns a Stripe Checkout link. If you already have Pro, ask to change it to Pro+. After you confirm, your existing subscription changes in place, keeps its billing interval and charges the price difference for the rest of the period immediately. To cancel, run customerio_cancel_subscription. Your paid plan continues to the end of the paid period.
Tell the AI what you wanted to do. It can send the request with customerio_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.