Google Optimize Replacement and GA4 Experiments: 5 Tools, Setup Steps, and How the Integration Works

Google Optimize was sunset in September 2023. GA4 does not include a built-in A/B testing tool as a direct replacement. GA4 functions as the analysis and reporting layer for experiments run through third-party testing platforms. The 5 confirmed GA4 experimentation partners are Optimizely, VWO, AB Tasty, Convert Experiences, and Crazy Egg.

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Google Help explains the official process in [GA4] Automatically collected events.

What Replaced Google Optimize?

Google Optimize was replaced by a GA4 integration model that connects third-party A/B testing platforms directly to GA4 via a public API. Google confirmed this approach after sunsetting Optimize, stating the focus would shift to enabling integrations with the most effective external experimentation tools rather than rebuilding a native testing tool inside GA4.

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Google ended Optimize and Optimize 360 in September 2023, citing the need to focus on integrating experimentation capabilities into GA4 and partner platforms. No Google-owned visual A/B testing tool exists as of 2025.

Why Did Google Sunset Google Optimize?

Google ended Optimize to redirect development resources toward GA4 and AI-driven analytics. Optimizely and VWO had existed as dedicated A/B testing platforms for over a decade before Optimize launched, with more advanced statistical engines, multivariate testing capabilities, and personalisation features.

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Does GA4 Have Native A/B Testing?

GA4 does not have a native A/B testing tool comparable to Google Optimize. GA4 serves as the measurement and analysis engine. Third-party platforms deliver the experiment, split the traffic, and serve the variants. GA4 receives experiment data as custom events and makes it available for reporting in the Explore section.

The GA4 experimentation model operates through 3 components:

1. Third-party platform: delivers variants and splits traffic between control and test groups
2. GA4 custom events: receive experiment ID and variant data from the third-party platform
3. GA4 Explore: segments experiment data by variant for conversion and behaviour analysis

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What Are the 5 GA4 Experimentation Partners That Replaced Google Optimize?

How Does Optimizely Integrate with GA4?

Optimizely is a digital experimentation platform founded in 2010. It supports client-side A/B tests, multivariate tests, server-side experiments, and feature flags. Optimizely's GA4 integration imports GA4 audiences into experiments for targeting and sends experiment data back to GA4 as event parameters.

Optimizely is suited for enterprise organisations with complex experimentation needs and large traffic volumes. It includes a WYSIWYG visual editor, warehouse-native scorecarding via BigQuery and Snowflake, and real-time audience segmentation.

How Does VWO Integrate with GA4?

VWO (Visual Website Optimizer) integrates with GA4 by pushing experiment data and user segments bidirectionally. GA4 audiences are available for targeting inside VWO experiments. VWO experiment results appear as event dimensions within GA4 reports.

VWO launched its official GA4 integration with support for events and segments, enabling experiment data to be analysed alongside all other GA4 behavioural data without switching platforms.

How Does AB Tasty Integrate with GA4?

AB Tasty connects to GA4 through client-side event tagging. Experiment variant data is sent to GA4 as a custom event parameter. GA4 Explore segments are then applied to compare conversion rates and behaviour metrics between control and variant groups.

AB Tasty supports A/B tests, multivariate tests, and personalisation campaigns. It includes a visual editor for no-code experiment setup.

How Does Convert Experiences Integrate with GA4?

Convert Experiences integrates with GA4 via a public GA4 API. The integration supports Bayesian and Frequentist statistical computation methods applied to GA4 conversion event data. Convert sends experiment and variant data to GA4 as event parameters, aligning experiment results with all GA4 reporting dimensions.

Convert Experiences pricing starts at $299 per month (billed annually). It includes session replay, 90 or more integrations, GDPR and CCPA compliance, and first-party cookie tracking.

How Does Crazy Egg Integrate with GA4?

Crazy Egg supports A/B testing with GA4 integration through event-based tracking. It adds heatmaps, session recordings, and scroll maps alongside experiment data, enabling visual diagnosis of why one variant outperforms another. Crazy Egg is suited for small to mid-sized teams that need combined CRO and A/B testing in a single tool.

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How Do You Run Experiments Using GA4 After Google Optimize Sunset?

Running experiments using GA4 requires a third-party testing platform and follows 5 steps:

1. Select a GA4-integrated A/B testing platform based on team size, traffic volume, and budget
2. Configure the platform to send experiment ID and variant name to GA4 as custom event parameters
3. Verify experiment data arrives in GA4 DebugView before launching the test to live traffic
4. Run the experiment until statistical significance is reached
5. Analyse results in GA4 Explore by creating a free-form report segmented by variant

How Do You Set Up GA4 to Receive Experiment Data?

Setting up GA4 to receive experiment data from a third-party platform follows 4 steps:

1. In the third-party platform, enable the GA4 integration and enter the GA4 Measurement ID
2. Configure the platform to fire a GA4 event containing 2 parameters: experiment_id and variant_id
3. In GA4, go to Configure > Custom Definitions and register experiment_id and variant_id as custom dimensions with the scope set to "Event"
4. Confirm the parameters appear in GA4 DebugView when a test page is loaded

Once registered, experiment data populates within 24 to 48 hours in GA4 standard reports and immediately in DebugView.

How Do You Analyse Experiment Results in GA4?

Analysing experiment results in GA4 follows 4 steps:

1. Open GA4 and navigate to Explore. Create a new free-form exploration.
2. Add the custom dimension variant_id as a row dimension.
3. Add the conversion event or key metric as the primary metric. Examples include purchase, generate_lead, and form_submit.
4. Apply a date range that covers the full experiment window. Compare conversion rates and metric values between the control and variant rows.

GA4 does not include a built-in statistical significance calculator for experiment results. Use an external significance calculator or the statistical engine built into the third-party testing platform to confirm results before declaring a winner.

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How Do GA4 Experiments Compare to Google Optimize?

Google Optimize 360 (the paid enterprise version) cost significantly more than its successor platforms. For teams that used the free version of Optimize, Crazy Egg and VWO provide the closest feature parity at accessible price points.

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Which GA4 Experimentation Tool Is the Best Replacement for Google Optimize?

The best replacement for Google Optimize depends on team size and use case:

• Small teams and solo marketers: Crazy Egg or PageTest.AI for accessible pricing and simple setup
• Mid-sized marketing teams: VWO or Convert Experiences for full GA4 integration, statistical rigour, and multivariate support
• Enterprise and developer-led teams: Optimizely for server-side testing, feature flags, BigQuery-native scorecarding, and advanced audience targeting from GA4

All 5 platforms send experiment data to GA4 as custom events, enabling centralised reporting inside GA4 Explore without leaving the analytics environment. The core analysis workflow in GA4 remains consistent across all platforms.