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Product News
March 27, 2025

Introducing Eppo's Event Logger: Accurate Assignments Made Easy

Eric Metelka
Before joining Eppo as Head of Product, Eric led experimentation programs at companies like Cameo and Cars.com

When you’re building software, enabling experiments or feature flags in production shouldn't leave you second-guessing if your implementation is correct. Integrating your event logging with your experimentation and flag tools can feel like a chore, especially if your team doesn’t already have the right infrastructure. And even with tools in place, how do you confirm everything works exactly as intended? Enter Eppo’s new Event Logger.

We designed our Event Logger to make implementation faster, easier, and stress-free, giving you visibility into the data moving through your system. Whether you’re spinning up a proof-of-concept (PoC) or refining your production setup, this tool streamlines the process of launching experiments while ensuring nothing slips through the cracks. It’s not about reinventing how logging works but solving a fundamental question instead: How can I be confident this is set up correctly? With Eppo, you’ll capture and surface logs in a way that makes them auditable, verifiable, and actionable.

The goal? Get back to shipping impactful features while we take the guesswork out of setup and validation.

Why Confidence in Setup Is Vital

It’s never just about logging events. It’s about knowing your feature flags and experiments are running exactly as designed. The Event Logger makes it easy to verify and audit your implementation, removing uncertainty so you can focus on creating real value. 

Here’s how it helps you stay ahead:

  • Validate with clarity: Get a clear view of the incoming data to confirm everything aligns with your intentions. Plus it’s all available in your warehouse for additional analysis.
  • Catch issues early: Address mismatches before they snowball into bigger problems or skew your results.
  • Integrate seamlessly: No configuration needed to get your assignment data set up and ready to start using to measure experiment impact.
  • Build stakeholder trust: When you have clear visibility into your setup, others can rely on the data without concern.

Most tools are pipes that send events to other places as needed. Eppo takes it a step further, ensuring you can track down issues, verify that things are working as expected, and maintain trust in your experiments and features. It’s not just about collecting data, it’s about giving you the confidence to trust it.

The Old Way of Handling Assignments

Previously, managing assignments in Eppo required a few extra steps, especially during PoCs. Here’s the high-level process teams followed to get started:

  • Bringing your own assignment logger/CDP (like Segment, Snowplow, or RudderStack). While capable, CDPs aren’t always built with experiments in mind, meaning a logger had to be in place. Any CDP works fine, an in-house logger is also an option, but teams without one would need to implement it from scratch.
  • Prepare your Event Logger/CDP to start tracking experiment assignments. This step involved implementing a logging callback function to record assignment events in your data warehouse, ensuring that every experiment, subject, variation, and timestamp was accounted for.
  • Teach Eppo how to identify your new experiment assignments. Once the assignment data was logged, users created Assignment SQL Definitions—SQL configurations to ingest and map this data back into Eppo for analysis.

Each of these steps required coordination between teams, custom development work, and potential delays.

The New Way with Eppo’s Event Logger

We built the Event Logger to make your life easier. Instead of wrangling integrations and custom queries, Eppo’s Event Logger handles all the heavy lifting for you. Now, you can log assignments directly from Eppo experiments without the extra complexity.

Key benefits of Eppo’s Event Logger:

  • Automatic assignment logging with zero extra setup needed.
  • Captures core experiment data like subject, variant, timestamp, and source, without the need to integrate with a separate event logger.
  • Works seamlessly with major data warehouses, so your stack stays compatible.

It’s the same trusted Eppo experience but with way less upfront work.

The Outcome?

Faster proof-of-concept launches. Less friction getting started. And more time to spend on your experimentation strategies instead of integration roadblocks.

The Choice is Yours, Find What Fits

Every team approaches logging assignments differently, and Eppo is designed to adapt to your unique needs. Whether you opt for Eppo's built-in Event Logger or integrate your own solution, like a CDP or an in-house solution, the decision isn’t about one being universally superior. It’s about choosing the approach that aligns best with your situation.

Why Choose Eppo’s Event Logger?

  • Fast Setup: Get up and running quickly without relying on external tools. Ideal for proof of concepts or products that don’t have logging infrastructure available.
  • Transparency: Monitor assignments as they happen, all within Eppo’s unified platform.

Why Use Your Own Logger?

  • Full Control: Keep your data private and in-house. Eppo won’t have visibility into what you log.
  • Flexible Scalability: Integrate seamlessly with other systems, like product analytics platforms, for a streamlined workflow.

Whatever path you choose, Eppo adjusts to meet your needs. Our support for external logging solutions remains robust, but if speed and simplicity are top priorities, Eppo’s Event Logger can help you hit the ground running.

Why Eppo Stands Out

Unlike traditional loggers, Eppo’s Event Logger is purpose-built for experimentation. It doesn’t try to be a full CDP or a sprawling behavioral analytics platform. Instead, it delivers exactly what you need to get experiments rolling quickly and reliably.

Get Started Faster Today

Experimentation should be empowering, not exhausting. With Eppo’s new Event Logger, we’re removing barriers, cutting down on setup time, and giving you the tools to focus on what matters most and make data-backed decisions with confidence.

Ready to experience it for yourself? Try Eppo’s Event Logger and see just how easy impactful experimentation can be.

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