Your Campaign Monitor API key is the credential that allows the Contact Form 7 Campaign Monitor Extension to communicate with your Campaign Monitor account. In other words, without a valid Campaign Monitor API key, the plugin cannot access your subscriber lists, add new contacts, or sync form submissions from your WordPress site.
Additionally, Campaign Monitor uses a straightforward API key authentication model. Unlike AWeber’s OAuth flow, Campaign Monitor gives you a single API key string that you copy and paste into the plugin settings. As a result, the entire setup process takes less than two minutes.
Furthermore, this guide walks you through finding your Campaign Monitor API key step by step and entering it into the Contact Form 7 Campaign Monitor Extension.
Where to Find Your Campaign Monitor API Key
Your Campaign Monitor API key is located in the account settings area. Specifically, follow these steps to find it:
- Log in to Campaign Monitor at campaignmonitor.com.
- Click your profile icon in the top-right corner of the dashboard.
- Select Account Settings from the dropdown menu.
- Click API Keys in the left sidebar under the account settings section.
- Copy your API key — Campaign Monitor displays your existing API key or lets you generate a new one.
In addition, users with Manager permissions can generate and view their own API keys. If you are a team member without Manager access, ask your account administrator to provide the Campaign Monitor API key.
Types of Campaign Monitor API Keys
Campaign Monitor provides two types of API keys. Specifically, it is important to use the right one for the Contact Form 7 Campaign Monitor Extension:
Account API key
This key gives access to all clients and lists under your Campaign Monitor account. In fact, this is the key most users need for the Contact Form 7 integration. It allows the plugin to list all your subscriber lists and add subscribers to any of them.
Client-specific API key
This key restricts access to a single client within your account. Moreover, agencies managing multiple clients in Campaign Monitor may prefer this approach for security. Each client gets their own API key, and the plugin can only access that specific client’s lists.
For most WordPress sites, the account API key is the correct choice. However, if you manage multiple clients in Campaign Monitor and want to limit the plugin’s access, use a client-specific key.
Entering Your Campaign Monitor API Key in WordPress
After copying your Campaign Monitor API key, follow these steps:
- Open your WordPress admin and navigate to Contact > Contact Forms.
- Edit the form you want to connect to Campaign Monitor.
- Click the Campaign Monitor tab that the extension added to the form editor.
- Paste your Campaign Monitor API key into the API Key field.
- Click Save — the plugin validates the key and loads your available subscriber lists.
As a result, a dropdown appears with your Campaign Monitor subscriber lists. Select the list you want form submissions sent to. You can also find the specific list by its Campaign Monitor List ID for precise control.
Common Campaign Monitor API Key Issues
Invalid API key error
If the plugin shows an “invalid API key” error after saving, check for trailing spaces or line breaks in the key. Specifically, copy the Campaign Monitor API key directly from the Campaign Monitor settings page and paste it without modifications. In fact, invisible whitespace characters are the most common cause of authentication failures.
API key works but lists do not load
This typically means you are using a client-specific API key for a client that has no active lists. Consequently, try using the account-level API key instead, which gives access to all clients and all lists.
Different API keys for different forms
Yes, each Contact Form 7 form can use a different Campaign Monitor API key. This is useful for agencies that manage multiple Campaign Monitor clients. Similarly, the Mailchimp API key setup supports the same per-form configuration.
Campaign Monitor API Key Security
Your Campaign Monitor API key grants access to your subscriber data. Therefore, follow these security practices:
- Never share your API key publicly — do not post it in forums, support tickets, or social media.
- Regenerate compromised keys — if you suspect your Campaign Monitor API key has been exposed, generate a new one immediately from the Campaign Monitor account settings.
- Use client-specific keys for agencies — if you manage multiple clients, use a dedicated API key per client to limit the blast radius if a key is compromised.
Most importantly, the Contact Form 7 Campaign Monitor Extension stores your API key securely in the WordPress database as post meta data. It transmits the key only to Campaign Monitor’s official API endpoint over HTTPS.
Next Steps
After entering your Campaign Monitor API key, you may also want to configure these features:
- Find your Campaign Monitor List ID — select lists by ID for precise subscriber routing.
- Add an opt-in checkbox — let visitors choose whether to subscribe.
Additionally, if you need help with your Campaign Monitor API key or any other aspect of the plugin, contact us directly.