How to Connect OptinMonster with Sendloop

OptinMonster offers seamless integration with Sendloop email marketing service. Connecting OptinMonster to your Sendloop email list is very easy.

In this article, you’ll learn how to connect Sendloop with OptinMonster.

Our native Sendloop integration is available with a Plus or higher subscription.
All subscription plans can add custom forms using the Form Embed block.

Before you start, as a best practice we recommend you also connect your campaigns to Monster Leads as a backup.

Connect Sendloop

When you create a campaign in OptinMonster that you intend to collect leads with, you’ll want to integrate with one or more services to send those leads to.

To send leads to Sendloop, follow these steps:

  1. Before you start, you’ll need a Sendloop API Key. You can create and copy an API Key from your Sendloop account following these steps:
    1. Log into your Sendloop account, click on your account name in the top right corner and select the Settings option.
      Open the Sendloop Settings page.
    2. Select the API Settings tab, here you can create or copy your API Key you wish to use with OptinMonster.
      Create or copy your Sendloop API Key.
  2. Returning to OptinMonster, navigate to the Integrations view in the campaign builder, search for and select Sendloop.
    Select Sendloop to integrate with OptinMonster.
  3. Enter a Sendloop Account Name (*internal use only) and your Sendloop API Key in the appropriate fields, then select the Connect to Sendloop button.
    Connect OptinMonster with Sendloop.
    *The Sendloop Account Name can be anything that helps you identify the specific integration within OptinMonster. It’s possible to add more than one Sendloop integration to your account and this is an easy way to differentiate between them when assigning integrations to individual campaigns.
  4. Required: Once the Sendloop integration has been connected select the Sendloop List you wish to send leads to from the Provider Lists field.
    Select a Sendloop List to add leads to.
  5. Optional: If your campaign is showing the Name and/or Phone fields you can specify the Custom Field ID for either.
    Set the custom fields for name and phone in Sendloop.
  6. When you are finished, Save your campaign.

Add Extra Fields

Our native Sendloop integration supports the following fields:

To add more fields to your campaign you’ll want to build the form as you wish it to appear using the Sendloop form builder, and add it to your campaign using our Form Embed block.

Get started adding a custom form to your campaign.

Email Automations

To send emails automatically to new leads you’ll want to configure email automations within your Sendloop account.


We strongly recommend you test the optin form before publishing your campaign to ensure it is working as you expect.

Before you begin, please be aware of the following details when testing Sendloop integrations:

  • Previously submitted or already subscribed leads may be treated differently by Sendloop than new leads. For this reason, we recommend using a completely unique email address each time you test submit your campaign’s form. You can use a free tool like or learn how to create unlimited unique email addresses from a single Gmail account.
  • If the lead is captured in Sendloop but you do not receive any automated emails it indicates the integration from OptinMonster to Sendloop is correct, and the issue is with the automated email configuration. Sendloop controls email automation exclusively. If you require assistance in troubleshooting email automations we recommend reaching out to Sendloop support directly.

Get started testing with the Live Site Inspector tool.

Spin-a-Wheel Support

If you are configuring a Gamified spin-to-win campaign, spin-a-wheel support is not available at this time to send the coupon data to Sendloop.

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Can I send leads to more than one List?

Yes! See our Lead Sharing guide to accomplish this.

How do I configure single or double opt-in?

See our guide on single vs. double opt-in.

Required: Sendloop handles the subscription mode on a per-list basis. New lists in Sendloop are configured with double opt-in by default. To change the subscription mode for your list, follow these steps:

  1. From your Sendloop dashboard, select Subscribers from the top menu. Then, select the list you would like to edit.
  2. From your list overview page, click on the Settings tab.
  3. Change the Subscription mode for your list to “subscribe after double opt-in confirmation” or “subscribe immediately” (single optin).
Is it possible for me to add a phone field to my campaign?

Yes! You can add a phone field. Learn how to capture phone numbers with OptinMonster.

Required: Sendloop handles custom fields on a per-list basis. To store phone numbers in Sendloop, you will need to create a custom field in your Sendloop email marketing list. Custom fields are added to each list individually, so if you would like to collect phone numbers on more than one list, you will need to repeat this process for each list. To do this, follow these steps:

  1. From your Sendloop dashboard, select Subscribers from the top menu. Then, select the list you would like to add a phone field to.
  2. On the next page, you will see an overview of your list. Click Add a new custom field under Custom Fields in the column on the right.
  3. Choose the type of field you’d like to add and add a custom label (optional). Click the Create button to add the field to your list.
  4. Once your custom field has been added successfully, click on the field from your list overview page.
  5. Copy your custom field’s unique ID and save it within your Sendloop integration in OptinMonster for the appropriate field and paste it in the corresponding Lead Options field in your Sendloop integration in OptinMonster.
Can I use Sendloop segments with my OptinMonster campaign?

Segments in Sendloop are not associated with subscribers individually. They operate like smart folders where a series of rules determines which subscribers match with the segment. Because of this, Sendloop segments cannot be connected to your OptinMonster campaign. You can still use segments in Sendloop to organize subscribers after they have been added to your list.


The campaign is capturing leads but shows 0 conversions in analytics.

Confirm that conversion tracking is turned on for the submit button in your campaign. See our guide on How to Enable Conversion Tracking.

Why am I receiving a “failed to connect” error when trying to connect Sendloop with OptinMonster?

This can happen if the API key you’re using has been revoked or if it has been configured to work on only specific IP addresses.

Check the API Settings in your Sendloop account. Make sure the API key you are using matches one of the currently active keys for your account. Also, check to make sure there are no Bound IPs associated with your API key. If necessary, try creating a new API key to connect to OptinMonster to resolve this issue.