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CRM ⇄ Communications

Apollo.io to Gmail integration — real-time, two-way sync

Keep Apollo.io and Gmail 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 Apollo.io and Gmail

Keep Apollo.io and Gmail working from the same contacts, and log every call, message, and meeting back on the record, in real time and in both directions.

Apollo.io holds the people the business talks to: the contacts, their phone numbers and email addresses, and which rep owns the relationship. Gmail is where the talking happens, whether that is calls, texts, email, or meetings. The two depend on the same people, and when the contact list in one drifts from the other, outreach goes to stale numbers and the record of what was said never makes it back to the account.

Stacksync syncs People (database records), Sequences, Deals (Opportunities), Tasks and calls in Apollo.io with Drafts, Attachments, History, Messages in Gmail field by field, in real time, and in both directions. Current contact details flow out to Gmail so it can reach the right person, and the calls, messages, and meetings Gmail produces flow back onto the matching record in Apollo.io. You decide which system owns which fields, and conflicts resolve by rules you set.

Common use cases

  • 01 Push CRM opportunity stages back into Apollo so reps see pipeline context while sequencing.
  • 02 Land sequence enrollment status and outcomes in a warehouse for outbound performance reporting.
  • 03 Read Attachments and message metadata into a warehouse or document store for retention, discovery, and compliance reporting.
  • 04 Mirror Labels with pipeline or ticket states so triage done in an external tool is reflected inside the inbox.

Common sync patterns

Calls, messages, and meetings on the record

Activity handled in Gmail appears on the matching contact and account in Apollo.io, so the next person sees the full history without leaving the CRM.

Where Gmail sends at scale: delivery and reply status back on the contact

Sends, bounces, opens, and replies from Gmail update fields on the contact in Apollo.io, so lead status reflects what actually reached the person.

One contact list, opt-outs included

A number, address, or unsubscribe recorded in either system updates the other, so no one calls a disconnected line or messages someone who opted out.

What you can sync between Apollo.io and Gmail

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.

Apollo.io objects Gmail objects How this pairing syncs
People (database records) Prospects from Apollo's global database, pulled into downstream systems once enriched or saved. Attachments File payloads referenced by message part; read out to storage or a document system for archival and compliance workflows. People (database records) is specific to Apollo.io and Attachments to Gmail — each maps to any object or custom field on the other side.
Sequences Outreach cadences (emailer campaigns in the API); enrollment status is read to track which contacts are being worked. History The incremental change log keyed by historyId; used for efficient delta sync so only mailbox changes since the last cursor are fetched. Sequences is specific to Apollo.io and History to Gmail — each maps to any object or custom field on the other side.
Deals (Opportunities) Pipeline records that can be read and written to keep Apollo aligned with the CRM of record. Messages Individual emails with headers, body, and label state; read out to a CRM or warehouse for activity logging, and sent or modified two-way from sales tools. Deals (Opportunities) is specific to Apollo.io and Messages to Gmail — each maps to any object or custom field on the other side.
Tasks and calls Rep activity records synced for activity reporting and coaching workflows. Threads Conversation groupings that keep replies together; synced so a CRM timeline or support desk shows the full exchange, not isolated messages. Tasks and calls is specific to Apollo.io and Threads to Gmail — each maps to any object or custom field on the other side.
Custom fields Account- and contact-level custom attributes mapped field-by-field in a sync. Labels User and system labels (INBOX, SENT, custom); applied and removed via sync to mirror pipeline stages or triage states from an external system. Custom fields is specific to Apollo.io and Labels to Gmail — each maps to any object or custom field on the other side.
Contacts People saved to your Apollo account, synced with emails, phone numbers, and enrichment fields. Drafts Unsent messages; created and updated from templates or sequence tools so reps review before sending from their own mailbox. Contacts is specific to Apollo.io and Drafts to Gmail — each maps to any object or custom field on the other side.

How changes propagate between Apollo.io and Gmail

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.

Apollo.io Gmail Interval-based propagation

DetectionStacksync polls Apollo.io for changes on an incremental schedule, reading only records changed since the previous pass. Polling on updated-at timestamps.

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

Gmail Apollo.io Sub-second propagation

DetectionGmail notifies Stacksync of record changes through webhook events. Incremental sync via users.history.list from a stored historyId cursor, plus real-time push notifications through Google Cloud Pub/Sub watch on the.

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

Rate-limit considerations

  • Apollo.io: Rate limits and enrichment credits vary by plan; bulk endpoints are throttled separately from single-record calls.
  • Gmail: Quota is measured in units per user per second (e.g. messages.list = 5 units, messages.send = 100 units) against a 250 quota-unit/user/second limit and a daily project cap; exceeding limits returns 429 with exponential backoff expected.
What ships with Apollo.io ⇄ Gmail

Connect Apollo.io and Gmail for flexible, real-time data sync.

Real-time sync, workflow automation, event queues, EDI, and monitoring, for every Apollo.io–Gmail connection.

Real-time

Two-way sync

Changes in Apollo.io or Gmail instantly reflect in both systems. No stale data, no manual imports.

No-code + pro-code

Workflow automation

Trigger automated workflows whenever Apollo.io or Gmail 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 Apollo.io or Gmail record.

Observability

Monitoring

Track your Apollo.io ⇄ Gmail sync health, view errors, and replay failed events in one click.

Trading partners

EDI

Transform legacy EDI complexity into simple database interactions between Apollo.io and Gmail.

How the Apollo.io and Gmail connectors work

Apollo.io

Integration surface
REST API
Authentication
API key (passed in request headers); master keys unlock account-wide endpoints
Change detection
Polling on updated-at timestamps; webhook callbacks exist only for delivering asynchronous enrichment results, not as a general change-event stream
Capabilities
read · write
Rate limits
Rate limits and enrichment credits vary by plan; bulk endpoints are throttled separately from single-record calls

Gmail

Integration surface
Gmail API (REST, v1)
Authentication
OAuth 2.0 via Google — user-authorized consent with granular scopes (gmail.readonly, gmail.modify, gmail.send, gmail.labels); restricted scopes require Google's app verification for production use
Change detection
Incremental sync via users.history.list from a stored historyId cursor, plus real-time push notifications through Google Cloud Pub/Sub watch on the mailbox (watch must be renewed at least every 7 days)
Capabilities
read · write · webhooks
Rate limits
Quota is measured in units per user per second (e.g. messages.list = 5 units, messages.send = 100 units) against a 250 quota-unit/user/second limit and a daily project cap; exceeding limits returns 429 with exponential backoff expected.
How it works

How to connect Apollo.io to Gmail — 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 Apollo.io and Gmail 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
    Apollo.io connected
    Gmail connected
    OAuth 2.0
    SSH tunnel
    SSL certificate
    VPC peering
  2. 02

    Choose tables

    Pick the Apollo.io and Gmail 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 · Apollo.io ⇄ Gmail
    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
    Apollo.io Gmail
    Company company_name text
    Email email text
    Amount amount numeric
    Created created_at timestamp
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FAQ

Apollo.io and Gmail 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.

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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 259 integrations available for Apollo.io and Gmail.

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