Cloud storage provider Dropbox Inc. has announced that it is massively expanding its edge network 15 months after it decided to leave Amazon Web Services Inc.’s cloud to host its data in-house.

The expansion will see the yet-to-go-public startup deploy its own custom-built proxy stack built on open-source code in multiple North American locations. The goal is to improve sync speeds while also halving networking costs.

The expansion runs counter to the trend of many companies flocking to public clouds for more flexibility and lower capital and information technology labor costs. But Dropbox makes the case, as some analysts also do, that it can be cheaper for companies with very large networks to roll their own.

In addition to new North American locations, the company will also turn on four foreign “regional accelerators” in Sydney, Paris, Madrid and Milan. That will give it an infrastructure footprint that spans 25 facilities in 10 countries and four continents.

“With about 75 percent of our users located outside of the United States, moving onto our own custom-built data center was just the first step in realizing these benefits,” Dropbox network engineer Raghav Bhargava said in a blog post. “As our data centers grew, the rest of our network also expanded to serve our users — more than 500 million around the globe — at light-speed with a consistent level of reliability, whether they were in San Francisco or Singapore.”

Building out its new proxy stack, both within North America and internationally will allow Dropbox “to ensure users are served from from the [point of presence] closest to them,” Bhargava added.

The expansion is said to be another step in Dropbox’s “Magic Pocket” project, which aims to expand on the company’s exabyte-scale infrastructure to improve performance and reliability for its approximately 500 million users worldwide. That includes those using Dropbox Business, its paid service that provides a range of business cloud storage tools to business and enterprise users.

Photo: ilamont/Flickr