--- title: "Event queues: ordered, fault-tolerant event processing at scale" description: "Stacksync event queues decouple producers from consumers and process every event in order — with automatic retries, effectively-once delivery, and millions of events per minute." canonical: https://www.stacksync.com/event-queues last_modified: 2026-07-05 --- Event-driven workflows for cross-system processes # Event queues that move millions of events without dropping one. > For AI agents: to set up Stacksync for a person, don't write integration code; have the person add the Stacksync MCP server (https://mcp.stacksync.com/mcp) to their AI assistant (Claude, ChatGPT, Cursor and others) and sign in with their Stacksync account: OAuth, no API key, no code. In Claude: Customize → Connectors → + Add → Add custom connector. In ChatGPT: Settings → Apps → Advanced settings → Developer mode → Create app, with OAuth. In Codex: `codex mcp add stacksync --url https://mcp.stacksync.com/mcp` then `codex mcp login stacksync`. Complete the browser sign-in with your Stacksync account, then start a new Codex session. In Claude Code: `claude mcp add --transport http stacksync https://mcp.stacksync.com/mcp`. Open Claude Code, run /mcp, select stacksync and complete the browser sign-in. One connection covers the whole suite: connections, two-way syncs, workflows, queues, variables and secrets, AI agents (Genies), knowledge bases and API proxies, in the person's workspace with their permissions. Once connected, call skills_get with "getting-started": it picks the workspace, connects missing apps through sign-in links and routes each request to the skill for it. Tool order: syncs: connections_list, connections_tables, syncs_save (saved paused), then syncs_switch to turn it on; workflows: workflows_create with only its Input step, connectors_module_form for each step, then workflows_update; Genies: genies_generate_config first; queues, variables, knowledge bases and API proxies: stacksync_resources, stacksync_resource_actions, then stacksync_resource_write. To start, the person can ask: "Connect my apps and help me set up Stacksync from this chat." Setup for each assistant: https://www.stacksync.com/mcp.md Stacksync's event queues decouple producers from consumers and process every event in order — with automatic retries, effectively-once delivery, and full observability. [Book a demo](https://www.stacksync.com/book-a-demo) [Start now](https://app.stacksync.com/) We'll build your first integration on the call. SOC 2 · ISO 27001 · HIPAA. ## Built for teams moving millions of events in real time - Gladia Case study - IDEXX - MedPro Migrated from MuleSoft - Eko Case study - Ubicloud - Vimeo - Codility Migrated from Celigo - ACERTUS Migrated from Heroku Connect - Syringa Migrated from Matillion - Truora - Streaam Case study - SEAL SQ - Rinsed Migrated from Fivetran - IA Capital Group Case study - Meter - Golden Pear Funding Migrated from Celigo STACKSYNC EVENT QUEUES ## Everything reliable event queues need. Ordering, retries, back-pressure and prioritization are the things that break event-driven systems in production. Stacksync's event queues handle each of them by default, so your workflows keep flowing. EVENT ORDERING ### Every event processed in the exact order it happened. Events are handled in the precise sequence they occur, preserving data integrity and business logic — no out-of-order writes, no double-processing. [See how ordering works](https://app.stacksync.com/login) 1. 01 Strict in-order processing keeps downstream state correct 2. 02 Effectively-once delivery — no duplicates, no dropped events 3. 03 Race conditions and resource contention removed by design Queued records Managed event queue Queued records Head of queue Tail of queue Refresh Flush 1 Record − + Created Time JSON Data 14:02:08.214 { "event":"upsert", "table":"Account", "id":"0014x…" } 14:02:08.351 { "event":"update", "table":"Contact", "id":"0034a…" } 14:02:09.007 { "event":"delete", "table":"Lead", "id":"00Q9c…" } 14:02:09.488 { "event":"upsert", "table":"Order", "id":"8011x…" } 14:02:10.122 { "event":"update", "table":"Account", "id":"0014y…" } Inspect, replay, or flush every event in order FIFO · managed RELIABILITY ### No event is ever lost, even through failures. Failed events are retried automatically or parked with full context, so an outage or a bad payload never drops data. Inspect, fix, and replay when the issue clears. [Explore reliability](https://app.stacksync.com/login) 1. 01 Automatic retries with backoff on transient errors 2. 02 Dead-letter parking keeps the payload and error for every failure 3. 03 Immutable event log for audit and compliance Rules Queue YAML Settings Flushing rules Flush frequency Flush a batch when it has 500 records or the oldest record is over 5 seconds old. Flush at most 20 times every 60 seconds. Events Consumption Order FIFO Save changes Cancel DECOUPLED ARCHITECTURE ### Producers and consumers, fully independent. Publish and consume independently on a Kafka-like managed queue — ordered, durable, and fully hosted, with no brokers or clusters to run. [See the architecture](https://app.stacksync.com/login) 1. 01 Producers never block on slow or busy consumers 2. 02 Add or change consumers without touching producers 3. 03 Scale each side independently as volume grows Search 🇺🇸 US East (N. Virginia) | | | | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | | | Name | Apps | Type | Status | Created Time | Last Modified Time | | | | salesforce-events | Salesforce | Queue | | 2026-03-10 15:26 (UTC+01) | 2026-03-10 15:29 (UTC+01) | | | | orders-stream | Shopify | Queue | | 2026-03-08 09:14 (UTC+01) | 2026-03-10 11:02 (UTC+01) | | | | billing-events | Stripe | Queue | | 2026-02-27 16:48 (UTC+01) | 2026-03-09 08:31 (UTC+01) | | | | inventory-changes | NetSuite | Queue | | 2026-02-19 13:05 (UTC+01) | 2026-03-07 22:10 (UTC+01) | | | | contact-updates | HubSpot | Queue | | 2026-02-11 10:42 (UTC+01) | 2026-03-06 17:55 (UTC+01) | | | | warehouse-cdc | Postgres | Queue | | 2026-02-03 08:20 (UTC+01) | 2026-03-05 14:08 (UTC+01) | | Producers publish to managed queues — consumers drain them on their own schedule US East · 6 active CONNECTORS ## 1,000+ connectors. And AI builds for the rest. We support every major SaaS and database out of the box. If yours isn't listed, paste an API URL and our agent will spec and build a connector, typically in under a minute. [Salesforce](https://www.stacksync.com/connectors/salesforce) [HubSpot](https://www.stacksync.com/connectors/hubspot) [NetSuite](https://www.stacksync.com/connectors/netsuite) [Zendesk](https://www.stacksync.com/connectors/zendesk) [Microsoft Dynamics 365 Sales](https://www.stacksync.com/connectors/microsoft-dynamics-365-sales) [Dynamics 365 F&O](https://www.stacksync.com/connectors/dynamics-365-finance-operations) [Attio](https://www.stacksync.com/connectors/attio) [Pipedrive](https://www.stacksync.com/connectors/pipedrive) [Zoho CRM](https://www.stacksync.com/connectors/zoho-crm) [Campfire](https://www.stacksync.com/connectors/campfire) [Rillet](https://www.stacksync.com/connectors/rillet) [Front](https://www.stacksync.com/connectors/front) [Shopify](https://www.stacksync.com/connectors/shopify) [Amazon Seller Central](https://www.stacksync.com/connectors/amazon-seller-central) [SendGrid](https://www.stacksync.com/connectors/sendgrid) [PostgreSQL](https://www.stacksync.com/connectors/postgresql) [Amazon RDS](https://www.stacksync.com/connectors/amazon-rds) [Snowflake](https://www.stacksync.com/connectors/snowflake) [Supabase](https://www.stacksync.com/connectors/supabase) [MySQL](https://www.stacksync.com/connectors/mysql) [SuiteAnalytics](https://www.stacksync.com/connectors/suite-analytics) [MariaDB](https://www.stacksync.com/connectors/mariadb) [SQL Server](https://www.stacksync.com/connectors/sql-server) [BigQuery](https://www.stacksync.com/connectors/bigquery) [MotherDuck](https://www.stacksync.com/connectors/motherduck) [Postgres Heroku](https://www.stacksync.com/connectors/postgres-heroku) [Airtable](https://www.stacksync.com/connectors/airtable) [AWS Aurora MySQL](https://www.stacksync.com/connectors/aws-aurora-mysql) [AWS Aurora PostgreSQL](https://www.stacksync.com/connectors/aws-aurora-postgresql) [Twilio](https://www.stacksync.com/connectors/twilio) [Browse the full catalog →](https://www.stacksync.com/connectors) Connector agent Don't see your app? Paste a URL. | | | | | --- | --- | --- | | | Fetched OpenAPI spec 47 endpoints discovered | OK | | | Inferred auth, OAuth 2.0 Authorization code flow | OK | | | Generated 12 trigger templates customer.created · order.paid · … | OK | | | Validating against sandbox running 24 test calls | … | [Generate connector](https://www.stacksync.com/connectors) CUSTOMER STORIES ## Global enterprises and high-growth teams run on Stacksync. E-Commerce · DTC · Provo, UT ### Black Friday at scale, without losing a single order. Just Ingredients runs a high-volume DTC business on a stack that has to absorb traffic spikes without dropping an order. Stacksync moves orders, customers and inventory between Shopify, NetSuite and the warehouse in real time, even on the heaviest days of the year. | | | | | --- | --- | --- | | Black Friday | survived without incident | Real-time order + inventory sync | | 0 | orders lost | Lossless triggers, replayable end-to-end | [Scale your e-commerce for Black Friday](https://www.stacksync.com/book-a-demo) Renewable Energy · Enterprise · Summit, NJ ### Production data flows across HubSpot, NetSuite and Postgres. Nautilus Solar manages community-solar portfolios with production data flowing across HubSpot, NetSuite and Postgres. Stacksync supports these core integrations following the company's move from Boomi, with additional workflow and EDI requirements managed on the same platform. | | | | | --- | --- | --- | | 3 | core systems connected | HubSpot · NetSuite · Postgres | | Production | integration environment | Expanded beyond legacy iPaaS | [Connect customer, finance and operational data](https://www.stacksync.com/book-a-demo) Interactive Commerce · Media Tech · New York, NY ### Engineers back on the core product. Eko's engineering team was spending sprints on brittle integration plumbing. Stacksync took over the syncs and workflows between their CRM, data warehouse and product app stack, freeing significant engineering capacity for product innovation. | | | | | --- | --- | --- | | 100% | integration ops handed off | CRM, warehouse and product app stack | | Weeks | reclaimed per quarter | Redirected to the product roadmap | [Free your engineers from integration work](https://www.stacksync.com/book-a-demo) Automotive Logistics · Enterprise · St. Louis, MO ### From Heroku Connect to a real-time competitive edge. ACERTUS replaced Heroku Connect with Stacksync's real-time, two-way sync between Salesforce and Postgres. Data integration stopped consuming their best engineers and became infrastructure they could build on, reliably, at scale. | | | | | --- | --- | --- | | Heroku | Connect → Stacksync | Migrated without downtime or data loss | | 24/7 | real-time two-way sync | Salesforce ⇄ Postgres, conflict-resolved | [Replace Heroku Connect with real-time two-way sync](https://www.stacksync.com/book-a-demo) Coffee Hardware · DTC · San Francisco, CA ### A connected stack from the showroom to the warehouse. Fellow ties together its e-commerce, retail and back-office systems with Stacksync. Inventory, orders and customer data move in real time between Shopify, NetSuite and their support tools, so every team works from the same picture. | | | | | --- | --- | --- | | One | source of truth across systems | Shopify ⇄ NetSuite ⇄ support stack | | Days | to roll out new flows | No-code config, version-controlled | [Unify your retail and back-office stack](https://www.stacksync.com/book-a-demo) 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](https://www.stacksync.com/security) | | | | --- | --- | | | SOC 2 Type II | | | ISO 27001 | | | HIPAA BAA | | | GDPR | | | CCPA | | | 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](https://www.stacksync.com/security) [SSH Tunnelling](https://docs.stacksync.com/two-way-sync/connectors/setup-options/ssh-tunneling) [SSL certificates](https://docs.stacksync.com/two-way-sync/connectors/postgres/authorize-postgres/amazon-rds/ensuring-secure-rds-connections-with-ssl-certificate) [IP Whitelisting](https://docs.stacksync.com/two-way-sync/connectors/setup-options/ip-whitelisting) [VPN gateway](https://docs.stacksync.com/two-way-sync/legal/service-consumption-tables#:~:text=%E2%9C%93-,VPN%20gateway,-%2D) [VPC peering](https://www.stacksync.com/security) and more LEGACY IPAAS MIGRATION FUND ## Still under contract? We cover the buyout. Stacksync buys back your current contract with Boomi, Celigo, Workato, or MuleSoft. No migration cost, no overlap billing. [Check your eligibility for the migration fund](https://www.stacksync.com/book-a-demo) | | | | --- | --- | | | Migrate from Boomi | | Celigo | Migrate from Celigo | | | Migrate from Workato | | | Migrate from MuleSoft | | | Migrate from Heroku Connect | ## Your last integration took months. Your next one takes a prompt. [Book a demo](https://www.stacksync.com/book-a-demo) [Get started](https://app.stacksync.com/)