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Storage ⇄ Business productivity

Amazon S3 to Customer.io integration — real-time, two-way sync

Keep Amazon S3 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 Amazon S3 and Customer.io

Land the records and documents that build up in Customer.io into Amazon S3 as they are created, and surface Amazon S3's file details on the Customer.io records that point to them, without an export job to maintain.

Customer.io and Amazon S3 hold different kinds of data. Customer.io carries records and the activity around them — the tickets, messages, orders, or issues a team works through, often with documents attached. Amazon S3 holds files and the metadata that describes them. Where the two meet is narrow but real: much of what Customer.io produces has to be kept somewhere durable, and many of the files Amazon S3 stores are the very documents Customer.io's records point to.

Stacksync syncs Events, Segments, Campaigns, Broadcasts in Customer.io with Object tags, Object versions, Prefixes (folders), Multipart uploads in Amazon S3 in real time. Records and attachments created in Customer.io are written into Amazon S3 as objects or files within seconds of being created. In the other direction, the metadata Amazon S3 keeps about those files — name, location, owner, modified date — flows back onto the matching record in Customer.io, so people see the current document without leaving the tool. Field-level mapping controls exactly what crosses over and in which direction, so you keep a durable copy of what matters without an extract to schedule or a nightly dump that leaves the copy a day behind.

Common use cases

  • 01 Keep unsubscribe and subscription-preference state consistent between Customer.io and the CRM to avoid compliance gaps.
  • 02 Sync account-level objects and their person relationships for B2B messaging keyed to company attributes.
  • 03 Two-way sync Object tags with a database so retention or classification labels set in an internal app write back onto S3 objects via the tagging API without rewriting the files.
  • 04 Mirror Objects under a given Bucket and prefix into another bucket, region, or a warehouse external stage for backup or downstream processing.

Common sync patterns

Feed a data lake or downstream pipeline

Structured records from Customer.io land in Amazon S3 as objects a data lake, search index, or processing pipeline can read, without a custom extract to build and babysit.

Archive what Customer.io produces into Amazon S3

Records and events from Customer.io — tickets, messages, orders, or issues — are written into Amazon S3 as objects or files as they change, giving you a durable, addressable copy for retention and audit.

Where Customer.io generates attachments: keep the files in Amazon S3

Documents attached to records in Customer.io land in the storage system automatically, with the source record holding a link back, so files live in one governed place instead of inside the tool.

What you can sync between Amazon S3 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.

Amazon S3 objects Customer.io objects How this pairing syncs
Objects Files stored under a key; content is read with GET and written with PUT, and each object's key/size/ETag/LastModified is the unit indexed into a database. Objects Non-person entities such as accounts or companies, related to people for account-level messaging. Same entity on both sides — records pair one-to-one and field-level changes reconcile in both directions.
Object metadata System metadata (Content-Type, size, ETag, LastModified) plus user-defined x-amz-meta-* headers; user metadata is fixed at write time and only changeable by rewriting the object. Newsletters Recurring email sends with performance metrics available for reporting syncs. Object metadata is specific to Amazon S3 and Newsletters to Customer.io — each maps to any object or custom field on the other side.
Object tags Up to 10 key-value tags per object, mutable in place via the tagging API independent of content, so classification and retention labels sync two-way without rewriting files. People Profiles with attributes, matched on identifiers like id or email; the main write target of data syncs. Object tags is specific to Amazon S3 and People to Customer.io — each maps to any object or custom field on the other side.
Object versions When bucket versioning is enabled every write creates a new version ID; prior versions and delete markers are readable for history and audit syncs. Events Behavioral events sent via the Track API that trigger campaigns. Object versions is specific to Amazon S3 and Events to Customer.io — each maps to any object or custom field on the other side.
Prefixes (folders) Logical path segments in object keys used to scope a sync and to parallelize throughput, since S3 rate limits partition by prefix. Segments Attribute- or event-based groups; data syncs feed the attributes segments evaluate. Prefixes (folders) is specific to Amazon S3 and Segments to Customer.io — each maps to any object or custom field on the other side.
Multipart uploads In-progress large-object uploads assembled from parts; objects above ~100 MB (required above 5 GB) are written this way, and incomplete uploads persist until completed or aborted. Campaigns Automated workflows whose membership and metrics can be read via the App API. Multipart uploads is specific to Amazon S3 and Campaigns to Customer.io — each maps to any object or custom field on the other side.

How changes propagate between Amazon S3 and Customer.io

Each direction of the sync is driven by what the source system can signal and what the destination accepts — detection, delivery, and expected latency below.

Amazon S3 Customer.io Sub-second propagation

DetectionAmazon S3 notifies Stacksync of record changes through webhook events. S3 Event Notifications push object-created, object-removed, and object-tagging events to SNS, SQS, Lambda, or EventBridge.

DeliveryEach detected change is written to Customer.io through its API, with automatic retries and rate-limit backoff.

Customer.io Amazon S3 Sub-second propagation

DetectionCustomer.io notifies Stacksync of record changes through webhook events. Reporting webhooks push message and delivery events.

DeliveryEach detected change is written to Amazon S3 through its API, with automatic retries and rate-limit backoff.

Rate-limit considerations

  • Amazon S3: S3 sustains at least 3,500 PUT/COPY/POST/DELETE and 5,500 GET/HEAD requests per second per partitioned prefix and scales higher automatically; bursts can return HTTP 503 SlowDown while it repartitions.
  • Customer.io: Subject to per-API rate limits documented by Customer.io.
What ships with Amazon S3 ⇄ Customer.io

Connect Amazon S3 and Customer.io for flexible, real-time data sync.

Real-time sync, workflow automation, event queues, EDI, and monitoring, for every Amazon S3–Customer.io connection.

Real-time

Two-way sync

Changes in Amazon S3 or Customer.io instantly reflect in both systems. No stale data, no manual imports.

No-code + pro-code

Workflow automation

Trigger automated workflows whenever Amazon S3 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 Amazon S3 or Customer.io record.

Observability

Monitoring

Track your Amazon S3 ⇄ 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 Amazon S3 and Customer.io.

How the Amazon S3 and Customer.io connectors work

Amazon S3

Integration surface
S3 REST API (also via AWS SDKs and the S3-compatible endpoint)
Authentication
AWS IAM credentials — an access key ID and secret access key signed with AWS Signature Version 4; supports temporary STS credentials and cross-account IAM roles
Change detection
S3 Event Notifications push object-created, object-removed, and object-tagging events to SNS, SQS, Lambda, or EventBridge; there is no modified-since query, so polling relies on each object's LastModified from ListObjectsV2
Capabilities
read · write · webhooks
Rate limits
S3 sustains at least 3,500 PUT/COPY/POST/DELETE and 5,500 GET/HEAD requests per second per partitioned prefix and scales higher automatically; bursts can return HTTP 503 SlowDown while it repartitions.

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 Amazon S3 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 Amazon S3 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
    Amazon S3 connected
    Customer.io connected
    OAuth 2.0
    SSH tunnel
    SSL certificate
    VPC peering
  2. 02

    Choose tables

    Pick the Amazon S3 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 · Amazon S3 ⇄ 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
    Amazon S3 Customer.io
    Company company_name text
    Email email text
    Amount amount numeric
    Created created_at timestamp
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FAQ

Amazon S3 and Customer.io integration FAQ

SECURITY

Security teams trust 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
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DPF US-EU-UK-CH
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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 408 integrations available for Amazon S3 and Customer.io.

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