Customer.io couldn't merge profiles
Startup co-founder on building a customer communication workflow
This exposed a core weakness in Customer.io’s original data model, it was great at reacting to events from one user record, but much worse at understanding one human across several signups. In a free trial business, the same eventual buyer might create multiple accounts with different emails before paying. If those profiles stay separate, onboarding, upgrade prompts, attribution, and reporting all treat one person like several unrelated leads, which breaks the full journey view.
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Customer.io centered workflows around an immutable customer ID, so once multiple trial accounts existed, the team could not combine them into one timeline. That meant past product activity, campaign engagement, and conversion signals stayed fragmented across separate profiles.
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This mattered more for free trial and product-led companies than for simple newsletter use cases. Customer.io’s strength was event driven messaging wired into the product through APIs or Segment, but that same developer first setup could leave teams with rigid profile structures and more engineering work to clean up edge cases.
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It also helps explain why some teams moved to tools like ActiveCampaign or Klaviyo. Those products were positioned as easier for non technical marketers to run day to day, and in Klaviyo’s case it was easier to merge profiles manually, which is valuable when one buyer shows up under several emails.
The market has moved toward making identity and data plumbing a bigger part of messaging platforms. Customer.io later expanded into Data Pipelines and a broader customer data layer, which points to where the category is heading, one profile, shared across messaging, analytics, and downstream tools, so growth teams can act on a person instead of a pile of disconnected accounts.