Identity stitching is the mechanism that links separate customer records into a single, unified profile when a common identifier connects them. It’s one of the core actions within identity resolution, which recognizes two profiles that appear unique as the same person and merges them into one.
Without identity stitching, you can end up with duplicate profiles and an incomplete picture of who your customers are. A customer who subscribes to SMS through a keyword opt-in creates one profile. When they later subscribe to emails through a sign-up form, that's another.
Identity stitching merges these records when a linking event occurs, like a purchase where the person provides both their phone number and email address. That way, you see everyone’s full history, all in one place.
How identity stitching works
Identity stitching is triggered when a customer provides multiple identifiers at the same time, like submitting both an email address and phone number during check-out. This allows the system to confirm both records belong to the same person.
The process typically follows a hierarchy of identifier strength. Email addresses generally serve as the primary identifier, with phone numbers and device IDs acting as secondary signals. When two profiles share a common identifier, they get merged into a single record, with the stronger identifier (typically email) becoming the anchor.
Two matching methods determine how profiles get stitched:
- Deterministic matching uses exact identifier matches like the same email address or the same phone number. High confidence, no inference required.
- Probabilistic matching uses signals like device type, location, and behavioral patterns to infer a likely match when no exact identifier overlap exists. Lower certainty, but extends coverage to anonymous or partially-identified users.
Identity stitching can also work retroactively. If someone browses your site anonymously, then later identifies themselves by clicking an email link or making a purchase, their previous browsing activity can be connected to their profile. This anonymous visitor backfill gives you a more complete view of the customer journey, even for activity that happened before you knew who they were.
Key features of identity stitching
A robust identity stitching system combines several capabilities to help maintain accurate customer records. Here are the core elements:
- Deterministic profile merging: Profiles only merge based on exact identifier matches, prioritizing precision over volume so teams can be more confident that merged profiles represent the same person.Real-time updates: Stitching happens as new data arrives, so profiles reflect current information without manual reconciliation.
- Anonymous activity backfill: Browsing behavior is stored and can be connected to a profile once the visitor identifies themselves by logging in, clicking an email, or completing a purchase.
- Typo and alias detection: Advanced systems can use “fuzzy matching” to identify profiles that appear to be duplicates due to email typos or aliases—for example, merging records that share the same phone number but have slightly different email addresses.
Benefits of identity stitching
Connecting customer data across touchpoints can create meaningful advantages for your marketing and customer relationships. Here are some ways it helps:
- Accurate personalization: Rather than tailoring messages to what one channel suggests, you can do so according to a customer’s full history with your brand, from browsing to buying to support interactions.
- Fewer duplicates and redundancies: Unified profiles help teams avoid sending the same person multiple messages or treating existing customers like new potential customers.
- More reliable inputs for AI: Predictive models can provide more stable insights when they draw from complete, deduplicated customer records.
- Consistent cross-channel experiences: When your marketing and support teams reference accurate data from the same comprehensive profile, customers don't have to repeat themselves or receive conflicting messages.
Identity stitching brings scattered interactions together into a coherent customer story, giving teams a stronger foundation for thoughtful, context-aware communication.
Klaviyo Data Platform automatically stitches customer identities across email, SMS, and on-site activity. Ready to personalize every message with full customer context? Get started with Klaviyo today.