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Data warehouse ⇄ Business productivity

Apache Druid to Customer.io integration — real-time, two-way sync

Keep Apache Druid and Customer.io in sync without custom scripts. Cut weeks of integration work, eliminate silent data drift, and give your team a single, reliable source of truth.

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Adopted by fast-scaling companies moving mission-critical data in real time

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Why teams connect Apache Druid and Customer.io

Get the data locked inside Customer.io into Apache Druid as live tables, and send results back where Customer.io can use them, without writing a pipeline.

Whatever Customer.io is used for, it accumulates data the rest of the company wants to analyze, and that data usually sits behind an API rather than in the warehouse. Building and babysitting an extraction pipeline is the tax most teams pay for it.

Stacksync syncs People, Objects, Events, Segments from Customer.io into tables in Apache Druid continuously, handling schema, rate limits, and retries. Because the sync is bi-directional, results computed in Apache Druid can also be written back into fields in Customer.io where the tool can use them.

Common use cases

  • Sync account-level objects and their person relationships for B2B messaging keyed to company attributes.
  • Sync product usage and billing attributes from Postgres onto Customer.io people so lifecycle campaigns trigger on real product behavior.
  • Sync Druid query results into a warehouse to combine real-time aggregates with historical models.
  • Keep lookup tables in Druid refreshed from a CRM or database so query-time joins use current reference data.

Cross-tool reporting

Combine Customer.io's data with data from every other synced system to answer questions no single tool can.

Where Customer.io accepts updates: operational write-back

Segments, scores, or reference values computed in Apache Druid sync back onto records in Customer.io, putting analysis where the work happens.

History that outlives the tool

A continuously synced copy in Apache Druid preserves a queryable record even as data ages out of Customer.io or gets changed inside it.

What you can sync between Apache Druid and Customer.io

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.

Apache Druid objects Customer.io objects
Dimensions String and categorical columns used for filtering and grouping in synced queries. Objects Non-person entities such as accounts or companies, related to people for account-level messaging.
Metrics Numeric columns, often pre-aggregated at ingestion via rollup. Events Behavioral events sent via the Track API that trigger campaigns.
Ingestion Supervisors Long-running specs that pull from streams like Kafka; the write path into Druid. Segments Attribute- or event-based groups; data syncs feed the attributes segments evaluate.
Lookups Key-value mappings joined at query time, refreshable from external systems. Campaigns Automated workflows whose membership and metrics can be read via the App API.
Tasks Batch ingestion and compaction jobs monitored during data loads. Broadcasts One-off sends to segments or audiences, triggerable via API.
Datasources The table-like unit of storage and querying, the main target of reads and ingestion. Deliveries / Messages Per-recipient message records whose lifecycle events flow out through reporting webhooks.
What ships with Apache Druid ⇄ Customer.io

Connect Apache Druid and Customer.io for flexible, real-time data sync.

Real-time sync, workflow automation, event queues, EDI, and monitoring, for every Apache Druid–Customer.io connection.

Real-time

Two-way sync

Changes in Apache Druid or Customer.io instantly reflect in both systems. No stale data, no manual imports.

No-code + pro-code

Workflow automation

Trigger automated workflows whenever Apache Druid or Customer.io 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 Apache Druid or Customer.io record.

Observability

Monitoring

Track your Apache Druid ⇄ Customer.io sync health, view errors, and replay failed events in one click.

Trading partners

EDI

Transform legacy EDI complexity into simple database interactions between Apache Druid and Customer.io.

How the Apache Druid and Customer.io connectors work

Apache Druid

Integration surface
REST API (SQL over HTTP and native JSON queries); JDBC via Avatica
Authentication
Deployment-dependent: basic authentication or an authenticator extension; often fronted by a proxy
Change detection
Not applicable for reads out (polling by time interval); data enters Druid through streaming or batch ingestion rather than row updates
Capabilities
read · write
Rate limits
No fixed API quotas; query concurrency is bounded by broker and historical node capacity

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
How it works

How to connect Apache Druid to Customer.io — 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.

  1. 01

    Connect your apps

    Authenticate Apache Druid and Customer.io with each platform's native method — OAuth, API keys, or service accounts — plus secure options like SSH tunneling, IP whitelisting, and VPC peering.

    • OAuth 2.0
    • SSH tunnel
    • VPC peering
    Apache Druid connected
    Customer.io connected
    OAuth 2.0
    SSH tunnel
    SSL certificate
    VPC peering
  2. 02

    Choose tables

    Pick the Apache Druid and Customer.io 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.

    • Standard objects
    • Custom objects
    • Auto-schema
    objects · Apache Druid ⇄ Customer.io
    Customers 12,480
    Sales Orders 8,213
    Invoices 5,902
    Items 1,344
  3. 03

    Map fields

    Fields map automatically even when names and types differ. Stacksync handles transformation and type casting for you, zero configuration required.

    • Auto-map
    • Type casting
    • Transforms
    Apache Druid Customer.io
    Company company_name text
    Email email text
    Amount amount numeric
    Created created_at timestamp
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FAQ

Apache Druid and Customer.io integration FAQ

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.

Learn more about security
SOC 2 type II
ISO 27001
HIPAA BAA
GDPR
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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:

OAuth 2 SSH Tunnelling SSL certificates IP Whitelisting VPN gateway VPC peering and more

Related integrations

Every pair below is a real-time, two-way sync. Search all 386 integrations available for Apache Druid and Customer.io.

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