OpenStreetMap scales to serve millions of users worldwide with Fastly

The challenge

OpenStreetMap (OSM) aims "to make a map of the world and to make that map data available to everyone who needs map data, whatever their use might be." Site Reliability Engineer and long time contributor Grant Slater likens the project to Wikipedia, but for mapping. With over 10 million registered contributors, OpenStreetMap has built an impressive global mapping resource. You’re likely using OpenStreetMap’s data every day with Apple, Pokemon Go, MapBox, and dozens of transit systems. As the project grew, the technical team faced significant infrastructure challenges that threatened their ability to deliver reliable map data to users worldwide.

The solution

The OpenStreetMap team turned to Fastly’s Fast Forward program, where millions of dollars in in-kind infrastructure is donated annually to the builders of the Open Web, to help manage their complex content distribution needs. As Slater explains, "we used to try to run our own CDN, and it was an absolute nightmare. It was so painful and it was becoming unsustainable." The global nature of OpenStreetMap's user base created unique challenges, as usage patterns follow the sun around the world. "Asia wakes up in the morning, and a lot of people are accessing the map tiles in Asia," Slater notes. "Then, later during the day, India wakes up and they have a high access pattern, and then Europe, and then East coast US."

OpenStreetMap implemented Fastly's CDN services to handle their raster tile generation service, which transforms raw map data into visual map tiles. This service constantly updates to reflect changes made by contributors every minute. Slater explains, "Thanks to how we've been able to customize the CDN using the VCL language that Fastly supports, we are able to put a number of controls in place" to manage the load across their infrastructure.

Managing unexpected traffic spikes without service disruption

OpenStreetMap regularly experiences dramatic traffic spikes that would overwhelm most systems. Slater recalls one particularly challenging event: "I woke up on a Sunday morning and saw all of our servers were completely overloaded, and it's because the official London Marathon runners trackers app decided to use OpenStreetMap data from our tile raster service during the event, maxing out our direct services." Without advance notice, the team had to quickly redirect traffic across their global infrastructure to maintain service.

The project also saw significant usage increases from popular applications that rely on their data. "The Pokémon Go game was amazing, like so many people jumped on because of that," Slater notes. "Tesla started to do a feature where you could summon your vehicle to come to you in parking spaces in public parking areas. That data they used came from OpenStreetMap. So we had a spike in people accurately mapping that data."

With Fastly's help, OpenStreetMap maintains an impressive 92% cache hit ratio, which Slater has been steadily improving: "I think we were at 88% cache hit ratio. And now we're up to about 92%." This efficiency allows their backend servers to focus on generating new content rather than repeatedly serving the same data, which ultimately improves response times and enhances the overall user experience, especially during traffic spikes.

Protecting data integrity with customized CDN controls

Beyond traffic management, OpenStreetMap faces challenges from abusive access patterns, particularly from AI data scrapers. "We've had a growing problem with AI data scrapers," Slater explains. "Effectively anonymous AI scraping companies just try to download everything, and in an abusive pattern they try to download every single version of every single page of every single bit of data as fast as they can."

Using Fastly's VCL capabilities, OpenStreetMap implemented customized rules to protect their infrastructure. "We've come up with access policies through Fastly's CDN, and we were testing out Fastly's new tools to block some of these abusive patterns," Slater notes. These controls allow legitimate users to access the data while preventing bad actors from overwhelming the system.

Moving to vector tiles for richer map experiences

Recently, OpenStreetMap launched a new vector tile service that represents a significant advancement over their traditional raster tiles. "The raster service effectively serves PNG files, images of a rendered map," Slater explains. "Vector data service, instead of serving images to the client, serves cut up data in a vector format. The browser or the app then injects its styling into that."

This new service, powered with Fastly’s edge cloud platform, ensures map data updates every minute, unlocking unprecedented speed and responsiveness. Minh Nguyễn, OSM's core software development facilitator, shares, "This service allows for much richer customization and language support, something that was previously challenging due to infrastructure limitations."

By leveraging Fastly’s ability to cache dynamic content at the edge and its superior Time to First Byte (TTFB), which is 32% faster than traditional CDNs, OpenStreetMap is able to deliver crucial updates and customizations in near real-time. Minh explains, "People are excited about the ability to see the whole map in their language. With Fastly’s advanced caching and real-time visibility tools, this is opening the possibility for people to customize the map without having to put in a lot of infrastructure of their own."

This collaboration highlights the scalability, performance gains, and developer-centric customization available through Fastly’s platform. OSM can now deliver superior digital experiences to global audiences, all while minimizing operational complexity and ensuring reliability.

Key takeaway

OpenStreetMap relies on Fastly's CDN services to deliver map data to millions of users worldwide while maintaining control over their infrastructure. "We manage the configuration of the CDN, but we know that it's up and it runs, and it's reliable. So it's such a great benefit to us," Slater says. By offloading content delivery to Fastly, the small volunteer team that runs OpenStreetMap can focus on improving their mapping data and services rather than managing complex global infrastructure.The result is a more responsive, reliable map service that continues to grow and evolve with global user needs, because OpenStreetMap isn’t just a map—it’s the foundational geographic data sustaining logistics, emergency response, and countless applications globally. Without OpenStreetMap a significant portion of the digital world’s ability to navigate, connect, and function would go dark.