---
ref: tool:loops/upsert-contact
name: Create or update a contact
company: company:loops
workflows: []
access: [mcp, cli, api]
tags: [capability:build-audience, category:email, has:api, has:cli, has:mcp]
docs: https://loops.so/docs/api-reference/update-contact
updated: 2026-09-27
---

# Create or update a contact

Updates the contact with a matching email address or user ID, or creates it, with properties and mailing list subscriptions.

Identify the contact by `email` or `userId`. To change a contact's email
address, it needs a `userId`: send the `userId` with the new address. Leave
`subscribed` out unless you mean to unsubscribe or re-subscribe the contact.
Set list membership with `mailingLists` (`--list <id>=true` on the CLI). On
the MCP server, `search`, `describe` and `execute` find, inspect and run this
operation.

## Set up

Use the first option your agent supports.

### MCP (official, remote)

Add this server to your agent's MCP settings, then sign in when asked.

```json
{ "mcpServers": { "loops": { "url": "https://mcp.loops.so" } } }
```

Call the MCP tool `execute`.

Server URL: https://mcp.loops.so

### CLI (official)

Install the command, then confirm it runs.

```sh
brew install loops-so/tap/loops
loops --version
```

Run `loops contacts update`.

Set `$LOOPS_API_KEY` in your environment first (get a key: https://app.loops.so/settings?page=api).

### API (official)

- Base URL: https://app.loops.so/api
- Endpoint: `PUT /v1/contacts/update`
- Auth: send the header `Authorization: Bearer $LOOPS_API_KEY`
- Get a key: https://app.loops.so/settings?page=api
- Docs: https://loops.so/docs/api-reference/intro

Before doing anything else, make one read-only call to confirm access.

## Rules

- Ask the user before anything that sends messages, costs money, or changes data.
- Never print API keys.