* ActiveCampaign
    * Deep Data requires a Plus plan
    * Deep Data requires a Customer to be created first
* AgileCRM
    * No API method for get custom fields
* ConvertKit
    * No visual way to manage webhooks
    * Contacts must be added with at least one tag
    * No “update” trigger for webhooks, just “tag_add"
* Drip
    * Updating a deleted contact doesn’t produce an error
    * Can’t update unsubscribed contacts
    * Multiple tags requires multiple API calls
* Infusionsoft
    * Length of password field
    * Unable to set field value with value of another field
* Gist
    * Can’t use on multiple sites since User ID is an identifier
* GetResponse
    * Can’t remove tags via API
    * Adding a contact gives an “Accepted” response, not a contact ID
* HubSpot
    * 25 lists limit in Starter / unlimited in Pro
    * No automation trigger for list removal
* Kartra
    * Can’t query all custom fields
* Klaviyo
    * Get lists requires checking each list individually
    * Get lists requires email address / CID lookup
* MailerLite
    * Can’t change email addresses
* Sendinblue
    * Contact ID is email address
* SendFox
    * Can’t change email addresses
    * No custom fields
    * Can’t get lists without loading contact first
    * Can’t apply lists without loading contact first
    * Multiple API calls to remove lists
    * No error codes from API
* Zoho
    * Tag limits: 10 on Standard, 30 on Professional, 50 on Enterprise