Real-time
Two-way sync
Changes in Customer.io or Lemlist instantly reflect in both systems. No stale data, no manual imports.
Business productivity
Customer.io to Lemlist integration — real-time, two-way sync
Keep Customer.io and Lemlist in sync without custom scripts. Cut weeks of integration work, eliminate silent data drift, and give your team a single, reliable source of truth.
- SOC 2 and 6 other compliance frameworks
- POC with real engineers in minutes
Adopted by fast-scaling companies moving mission-critical data in real time
Case study
Migrated from Mulesoft
Case study
Migrated from Celigo
Migrated from Heroku Connect
Migrated from Matillion
Case study
Migrated from Fivetran
Case study
Migrated from Celigo
Why teams connect Customer.io and Lemlist
Stop re-entering the same information in Customer.io and Lemlist: Stacksync keeps the records they share consistent in real time, in both directions.
Two tools in the daily stack often hold overlapping information: the same people, the same companies, or the same pieces of work, described twice. The tools do different jobs, so consolidating is not the answer; the overlap just needs to stop drifting.
Stacksync syncs Segments, Campaigns, Broadcasts, Deliveries / Messages in Customer.io with Campaigns, Leads, Activities, Unsubscribes in Lemlist in real time. You choose which records overlap, map the fields that should match, and pick a direction or let changes flow both ways. From then on, an update made in either tool is reflected in the other within seconds, without exports or copy-paste.
Because the sync is field-level, each tool keeps its own extras; only the shared data is held in agreement.
Common use cases
- Land delivery and engagement events (sent, opened, clicked, bounced) from reporting webhooks into a warehouse for attribution analysis.
- Keep unsubscribe and subscription-preference state consistent between Customer.io and the CRM to avoid compliance gaps.
- Stop or pause sequences automatically when a reply converts to a deal in the CRM
- Mirror campaign performance data into BI tools for outbound reporting across senders
Where both tools track people or companies: one consistent record
Contact and company details corrected in either tool update the other, so nobody works from the old version.
Where one tool produces events: mirror them in the other
Payments, replies, messages, or tickets created in one tool can create or update matching records in the other, keeping context in one place.
Where Lemlist is where the team documents or plans: keep its data fed
Information that originates in Customer.io stays current in Lemlist instead of going stale after a one-time paste.
What you can sync between Customer.io and Lemlist
Representative objects on each side — any object or custom field can map to any target. Schemas are auto-detected; types are converted between the two systems.
| Customer.io objects | Lemlist objects | |
|---|---|---|
| Deliveries / Messages Per-recipient message records whose lifecycle events flow out through reporting webhooks. | Unsubscribes Opt-out records propagate to other outreach tools and the CRM for compliance. | |
| Newsletters Recurring email sends with performance metrics available for reporting syncs. | Webhooks Hook subscriptions define which activity events are pushed to external endpoints. | |
| People Profiles with attributes, matched on identifiers like id or email; the main write target of data syncs. | Team Members Sender and seat records map outreach activity to reps in other systems. | |
| Objects Non-person entities such as accounts or companies, related to people for account-level messaging. | Campaigns Outreach campaigns are the container leads are pushed into from CRMs and list-building workflows. | |
| Events Behavioral events sent via the Track API that trigger campaigns. | Leads Per-campaign prospect records sync in from enrichment sources and back out with status. | |
| Segments Attribute- or event-based groups; data syncs feed the attributes segments evaluate. | Activities Engagement records such as opens, clicks, replies, and bounces sync to CRM timelines. |
What ships with Customer.io ⇄ Lemlist
Connect Customer.io and Lemlist for flexible, real-time data sync.
Real-time sync, workflow automation, event queues, EDI, and monitoring, for every Customer.io–Lemlist connection.
No-code + pro-code
Workflow automation
Trigger automated workflows whenever Customer.io or Lemlist data changes, update records, fire webhooks, or kick off sequences without brittle API scripts.
At scale
Event queues
Handle millions of events per minute without losing a single Customer.io or Lemlist record.
Observability
Monitoring
Track your Customer.io ⇄ Lemlist sync health, view errors, and replay failed events in one click.
Trading partners
EDI
Transform legacy EDI complexity into simple database interactions between Customer.io and Lemlist.
How the Customer.io and Lemlist connectors work
Customer.io
- Integration surface
- REST APIs split by purpose: Track API for data ingestion, App API for campaigns, people lookups, and messages
- Authentication
- Basic auth with site ID and API key for the Track API; bearer token for the App API
- Change detection
- Reporting webhooks push message and delivery events; person attribute changes are not streamed and require source-side detection
- Capabilities
- read · write · webhooks
- Rate limits
- Subject to per-API rate limits documented by Customer.io
Lemlist
- Integration surface
- REST API
- Authentication
- API key
- Change detection
- Webhooks on outreach activity events, plus polling
- Capabilities
- read · write · webhooks
- Rate limits
- Subject to the platform's API rate limits
How it works
How to connect Customer.io to Lemlist — three steps, no code
Configure and sync within minutes, no code. Whether you sync 50k or 100M+ records, Stacksync handles the queues, infra, and plumbing. Integrations are non-invasive and need zero setup on your systems.
- 01
Connect your apps
Authenticate Customer.io and Lemlist with each platform's native method — OAuth, API keys, or service accounts — plus secure options like SSH tunneling, IP whitelisting, and VPC peering.
Customer.io
connected
Lemlist
connected
OAuth 2.0SSH tunnelSSL certificateVPC peering - 02
Choose tables
Pick the Customer.io and Lemlist objects to sync — Stacksync auto-detects both schemas, including custom fields where the platform exposes them. Sync to existing tables, or let Stacksync create new ones with ideal data types.
objects · Customer.io ⇄ LemlistCustomers 12,480Sales Orders 8,213Invoices 5,902Items 1,344 - 03
Map fields
Fields map automatically even when names and types differ. Stacksync handles transformation and type casting for you, zero configuration required.
Customer.io LemlistCompany company_name textEmail email textAmount amount numericCreated created_at timestamp
FAQ
Customer.io and Lemlist integration FAQ
-
Yes. Stacksync provides a managed, real-time two-way integration between Customer.io and Lemlist: authenticate both systems, choose the objects to sync (such as Customer.io's Deliveries / Messages and Newsletters), map fields visually, and changes propagate both ways in milliseconds — no code required.
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Yes. Each object mapping can be bidirectional or restricted to a single direction (both systems accept writes). Read-only mirrors, one-way pushes, and full two-way sync can be mixed in the same integration.
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Common patterns for Customer.io and Lemlist: Where both tools track people or companies: one consistent record; Where one tool produces events: mirror them in the other; Where Lemlist is where the team documents or plans: keep its data fed. Contact and company details corrected in either tool update the other, so nobody works from the old version.
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Customer.io: REST APIs split by purpose: Track API for data ingestion, App API for campaigns, people lookups, and messages. Authentication: Basic auth with site ID and API key for the Track API; bearer token for the App API. Lemlist: REST API. Authentication: API key. Stacksync manages authentication, retries, and rate limits on both sides.
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Customer.io: Beyond people, Customer.io supports non-person objects (for example accounts) with typed relationships to people, enabling account-based messaging logic. Lemlist: Activity events such as replies, opens, bounces, and unsubscribes can be delivered via webhooks, enabling near real-time updates to CRM records without polling every campaign. Stacksync's field mapping accounts for these differences between Customer.io and Lemlist without custom code.
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Stacksync is SOC 2 Type II and ISO 27001 certified with HIPAA BAA support. Data is encrypted in transit, and a zero-persistent-storage architecture means Customer.io and Lemlist records are not retained after a sync operation.
SECURITY
Security teams love Stacksync
As a data company, we understand the importance of keeping your data secure. Stacksync is built with security best practices to keep your data safe at every layer, and is DPF-certified for US, EU, UK and CH data transfers.
SOC 2 type II
ISO 27001
HIPAA BAA
GDPR
CCPA
CSA STAR
DPF US-EU-UK-CH
→ SECURITY WITH BENEFITS
SSO & SCIM
Let your users access Stacksync from your centralized user management systems. Works with Okta, Azure, Google SSO and more.
Alerts
Immediately get alerted about record syncing issues over email, Slack, PagerDuty and WhatsApp. Resolve issues from a centralized dashboard with retry and revert options.
Secure connection options
Securely connects to your systems with:
Related integrations
Every pair below is a real-time, two-way sync. Search all 386 integrations available for Customer.io and Lemlist.
Popular · 8 of 386
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Customer.io ⇄ Amazon Seller Central -
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Customer.io ⇄ Twilio -
Customer.io ⇄ GitHub -
Lemlist ⇄ Zendesk -
Lemlist ⇄ Campfire -
Lemlist ⇄ Front - Lemlist ⇄ Amazon Seller Central
No integrations match .
