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The Open-Source Hub & Spoke: Eliminate Wasted Ad Spend with Synchronized Audiences

Are you burning money showing retargeting ads to customers who have already converted? When a lead submits a contact form, they might be removed from your Google Ads remarketing list, but continue seeing the same ads on Facebook for days. This delay in audience synchronization wastes your budget, creates a poor user experience for new customers, and makes your performance data inaccurate.

This playbook shows you how to build a powerful 'Hub & Spoke' marketing stack on a minimal budget. Using the free, open-source RudderStack as your central data hub (the 'Hub'), you capture lead data once—like a form submission. RudderStack then instantly relays this conversion event to all your connected tools (the 'Spokes'), like HubSpot, MailerLite, Google Ads, and Facebook. The result: a converted lead is automatically and immediately removed from all retargeting audiences across all platforms.

Expected Outcomes

  • Drastically reduce wasted ad spend by instantly removing converted leads from retargeting campaigns.
  • Ensure real-time audience synchronization between Google Ads, Facebook Ads, and other platforms.
  • Improve the post-conversion customer experience by eliminating irrelevant ads.
  • Centralize all customer data and conversion events into a single, reliable system.
  • Build a powerful, enterprise-grade marketing automation stack for a fraction of the typical cost.

Core Tools in This Stack

RudderStack

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RudderStack is a composable Customer Data Platform (CDP) built for developers. It enables businesses to collect customer data from every source, unify it in their existing data warehouse, and activate it across their entire tool stack.

Key Features
  • Composable architecture
  • Event Stream for data collection
  • Warehouse Actions (Reverse ETL)
  • Identity Resolution
  • Real-time Audience Builder
  • Profiles API for unified customer views
  • Extensive source and destination integrations
Ideal For

Company Size: Micro, Small, Medium, Large

Industries: Technology & Software, Business & Professional Services, Retail & E-commerce, Creative & Media, Other

Pricing

Model: Free Tier, Usage-Based, Custom/Enterprise

Tier: Mid-range

Ease of Use

Medium

HubSpot CRM

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A comprehensive CRM platform that includes a suite of tools for marketing, sales, content management, and customer service, with a completely free CRM at its core to help businesses manage customer relationships and accelerate growth.

Key Features
  • Contact & Lead Management
  • Sales Pipeline Visualization
  • Deal Tracking and Management
  • Email Tracking and Templates
  • Meeting Scheduling Tool
  • Live Chat and Chatbots
  • Reporting and Analytics Dashboards
  • Task and Activity Automation
Ideal For

Company Size: Small, Medium

Industries: Technology & Software, Business & Professional Services, Retail & E-commerce, Creative & Media

Pricing

Model: Freemium, Subscription

Tier: Starter

Ease of Use

Very High

MailerLite

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An all-in-one digital marketing platform that helps businesses of all sizes grow their audience and revenue through email marketing, automation, websites, and landing pages.

Key Features
  • Email Automation
  • Drag & Drop Editor
  • Landing Pages & Websites
  • Signup Forms & Pop-ups
  • A/B Testing
  • E-commerce Integration
  • AI Content Generation
  • Segmentation
Ideal For

Company Size: Micro, Small, Medium

Industries: Technology & Software, Business & Professional Services, Retail & E-commerce, Creative & Media, Education & Non-Profit, Health & Wellness, Other

Pricing

Model: Freemium, Subscription

Tier: Low

Ease of Use

Beginner

The Workflow

graph TD subgraph "Open-Source Hub & Spoke" direction LR N0["RudderStack"] N1["HubSpot CRM"] N2["MailerLite"] N0 -- "Forwards `identify` calls to create/update contacts" --> N1 N0 -- "Forwards `identify` calls to create/update subscribers" --> N2 N0 -- "Forwards `track` events to log custom activities" --> N1 N0 -- "Forwards `track` events to add subscribers to groups" --> N2 end classDef blue fill:#3498db,stroke:#2980b9,stroke-width:2px,color:#fff; classDef green fill:#2ecc71,stroke:#27ae60,stroke-width:2px,color:#fff; classDef orange fill:#f39c12,stroke:#d35400,stroke-width:2px,color:#fff; class N0 blue; class N1 blue; class N2 blue;

Integration Logic

  • RudderStack Event Stream

    This integration uses RudderStack as a central Customer Data Platform (CDP) to collect event data (such as page views, user identification, and custom actions) from a source like a website or mobile app. When an `identify` call is made, RudderStack forwards the user's traits to HubSpot to create or update a contact record with the latest attributes. Simultaneously, the same `identify` call is sent to MailerLite to create or update a subscriber. `track` events can be used to log custom activities on the HubSpot contact timeline and to add MailerLite subscribers to specific groups, enabling behavior-based segmentation for email campaigns.

Unlock the Wasted Ad Spend Playbook

Learn to synchronize your ad audiences in real-time to stop showing ads to converted customers.