Split scales 1000x with Fastly to deliver trillions of feature flags and experiments each month

When Split opened for business, one of the first building blocks they were looking for was an edge cloud network to serve as the medium for delivering feature flags to their customers. The top of their priority list was scalability and reliability, which is why they chose Fastly. Split’s customers adopt feature flags to introduce and roll back changes as nimbly as possible, by reducing the median time to recovery. When evaluating conventional CDNs, Split was experiencing purge times ranging from 10 to 30 minutes. “That would be ridiculous,” says Patricio “Pato” Echagüe, Chief Technology Officer and co-founder. “I can’t tell a customer that.” With Fastly’s edge cloud network, Split is getting sub-second purge times in most cases—a difference of nearly 200%.

Today, Split is evaluating flags for 1.5 billion named and unnamed users. By delivering flags from the edge and strategically shielding their origin with Fastly, the company can maintain reliably high performance even as traffic peaks. According to Echague, at a time when Split was getting 120,000 requests per second, all but 54 went to Fastly and were responded to at the edge. Echagüe says, “Without Fastly’s shielding, I can tell you that would not be possible.”

As a company with a worldwide customer base, Split also relies on Fastly’s global network to maintain high uptimes in every location. With SLAs offering uptimes as low as 99.99%, passing the responsibility to Fastly for detecting degradation in one region and retrying in different regions removes the potential for human error and allows them to provide performance at scale.

Developer tools and high-touch support accelerate updates

Split also credits both Fastly’s ease of use and Enterprise Support with helping them grow. When the company was just starting, launching and operating a CDN was new territory for the founders. Fastly documentation provided enough guidance to get them started in their early days. As the company grew—both in customer numbers and in complexity—it helped to know that support was always available while developing new features or modifying code.

Not only has Fastly support been available 24/7, but at times they’ve been known to reach out proactively to help. Nicolas Espejo, Cloud Engineering Manager, recalls starting out with the Edge Dictionary feature, which allows Fastly customers to create dictionaries within their Fastly services. After discussing it with a member of the support team, Espejo got a direct message from another Fastly engineer suggesting an even better way to solve the problem Split was working on, for a better end result.

VCL is another Fastly tool Split uses to optimize deployments. Echague says he wasn’t familiar with VCL before starting to use Fastly, but once he started, “It was like black magic.” For Split, there’s peace of mind knowing that there’s always a way to do something, whether you want to DIY it or make it simple by adding a Fastly Fiddle. Echagüe and Espejo have also started exploiting Fastly’s integration with Terraform via API, which has reduced the likelihood of human error and allowed them to move more quickly through the development cycle. Split plans to manage all code changes in Terraform within the next quarter, to make it easier for everyone to review code and then quickly implement changes.

Fastly features help Split deliver for customers

Another ingredient for successful scaling is real-time observability. Split takes advantage of Fastly integrations with Sumo Logic and syslogs for real-time insights into their traffic. That’s been useful for routine monitoring as well as managing unexpected spikes. Not long ago, Split noticed that the corporate website was receiving 10 times more traffic than usual, with no obvious cause. Pantheon, a website management partner powered by Fastly and used by Split, saw the traffic increase and asked whether the company needed a size upgrade. Reviewing Fastly logs, they saw that a specific customer had made a change that sent thousands of requests at once, out of the blue. Split was able to fix it right away and keep traffic flowing.

Most recently, Split added Fastly Image Optimizer to their stack. Because Google penalizes sites that are not serving the right image size for a specific requesting device, using Image Optimizer helps improve SEO for Split and their customers. Optimizing at the edge also helps serve images faster.

Finally, Split names Fastly’s predictable pricing as an important feature that’s freed them to grow. In many cases CDN vendors charge for a variety of things, sometimes unexpectedly, so that CDN costs can vary dramatically over time. “Fastly is very clear,” Echagüe says, “so I don’t have to think about it or worry that making a change will add charges to our bill, and that's important to me.”