Your Loops API key should never be used client side or exposed to your end users.

Start here if you want to use the Loops API to add contacts to your Loops audience, update their attributes, and send events to Loops.

Rate Limiting

To ensure the quality of service for all users, our API is rate limited. This means there’s a limit to the number of requests your application can make to our API in a certain time frame. The baseline rate limit is 10 requests per second per team.


Sometimes things go wrong. Here are some tips to help you debug your API requests.

OpenAPI spec

Get started quickly with the Loops API using our OpenAPI documents.

You can import these documents into an API client like Postman or Insomnia to see and use all of our endpoints, with example requests and expected responses.


The following are SDKs built on top of the API, making it easier to integrate in your project.

API Reference


Manage contacts with the API.


Send events to trigger emails in Loops.

Transactional email

Send a transactional email with the API.

Custom fields

Get a list of your account’s custom contact properties.

API key

Test your API key.

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