In January of last year, AtomicJar, an early-stage firm that seemed to be taking off, raised a substantial $25 million Series A, even by today’s standards. Building a commercial container testing platform off the back of a well-liked open source project is always a good idea. It would have seemed that the startup should have found product-market fit and taken off, but instead it chose to collaborate with Docker, the company that originated the concept of containers.

Docker said today that it has acquired AtomicJar and integrated the 19 staff members into its newly formed testing business. The purchase price was undisclosed to both corporations, but it was sufficient to remove a well-funded startup with great promise off the market.

According to CEO Scott Johnston, Docker has been developing a full suite of build, test, and deploy services on the Docker platform specifically for developers who are working on projects prior to going live. The business is effectively purchasing the testing component of this equation by purchasing AtomicJar.

Being one of the top ten most downloaded apps in the Docker marketplace and being developed on top of Docker didn’t hinder the startup. According to pulls or downloads, “Testcontainers consistently ranks in the top 10 with millions of pulls or downloads per month, as well as [hundreds of thousands of] unique IP addresses,” Johnston informed reporters. This results in more than 600,000 distinct IP addresses per month, which is equivalent to millions of pulls of Testcontainers.

What precisely does Docker receive? “A big testing issue for developers is that they have been using a representation of the testing components, rather than the actual software, and they often lacked confidence that these tests were actually reproducing what would happen in a live environment,” AtomicJar co-founder Sergei Egorov told reporters at the time of the Series A funding. By testing against actual versions of the required software components, testcontainers altered that.

Egorov stated that while his investors usually advise businesses in his stage of development to continue growing, he wasn’t specifically aiming to sell the company. Nevertheless, he felt that this was a good fit and that the offer was compelling, so he chose to proceed.

“We felt that now is the right time for us to join forces because of the shorter path to liquidity combined with a strong product and cultural alignment between Docker and AtomicJar,” Egorov told reporters. “The year and market were obviously challenging, but not more challenging than for the rest of the industry,” he added.

While he typically advises founders to stick with it for the long run, Ed Sim, managing partner at Boldstart, an early investor in AtomicJar, notes that his firm invests early—even before the company is incorporated—so it’s for a competitive price and the founders always have the option to sell or keep going.

“We’re more than delighted to go with the process if the founders think this is a good time to join forces with another company, and considering where we are on the cap table, we’re going to do fairly well, along with the founders,” he stated.

In AtomicJar’s instance, Sim stated that both he and the Boldstart team were excited about the transaction and that he believes Docker is building a strong business. We are all really excited, I must say. The A round was hardly even utilized by the corporation. With just 19 employees, it is a small staff. Thus, he remarked, “This is a lean, mean, efficient team that is currently experiencing insane open source traction.”

In 2015, Richard North, a co-founder of AtomicJar, launched the first Testcontainers open-source project. In 2021, he and Egorov got in touch to begin developing the for-profit business on top of the open-source initiative, which attracted users including Capital One, Netflix, Uber, and Spotify. Prior to the acquisition today, the company had raised a total of $29 million.