Mark Russinovich, the Microsoft Azure CTO, posted a tweet in September 2022 that surprised the software world — declaring that it was time to avoid starting new projects in C or C++, the languages historically used to build Windows, Office, and other core Microsoft software.
For the sake of security and reliability, he advised using the Rust programming language — a modern open-source alternative with a quirky orange crab mascot — in situations where software can’t rely on what’s known as a garbage collector, the system that automatically clears unused data from memory.
It surprised Satya Nadella, too. A few hours later, an email landed in Russinovich’s inbox from the Microsoft CEO, asking if he was serious.
Yes, he replied, he was.
Russinovich recounted this story in his recent keynote address at RustConf 2025 in Seattle. The Microsoft cloud leader explained that for two decades, roughly 70% of Microsoft’s security vulnerabilities have been due to memory safety issues — the very class of bugs to which C and C++ are susceptible, and which Rust was designed from the ground up to prevent.
“No matter how much we really want to make C and C++ better,” Russinovich told the crowd of software developers, “we can’t make it as good as what Rust starts with.”
From community project to core infrastructure
Microsoft has doubled down on Rust in the years since that exchange, using the programming language across many of its products. If you’re running a recent version of Windows, you can find a file in your System32 directory called win32kbase_rs.sys. The “rs” stands for Rust.
It’s part of a groundswell of support across the software industry for memory-safe languages, from the National Security Agency to the Linux operating system kernel.
Rust, first developed at Mozilla Research in the mid-2000s, has become a core strategic component for some of the world’s largest tech companies, including Microsoft, Amazon, Google and Arm.
This year’s event, Sept. 2-5, marked the 10th anniversary of Rust’s first stable release, a milestone that underscores both progress and growing pains as Rust evolves from cult favorite to critical infrastructure. Sessions focused on both success stories and practical realities.
Adopting a new technology in a large organization is “wildly expensive,” cautioned Amazon engineer Russell Cohen in one session. “You’re not just adopting a language, you’re adopting an entire stack of technologies that teams have to be familiar with in order to be effective.”
Cohen said teams at Amazon without a Rust expert to help shepherd the project are 40% more likely to give up on Rust. He shared a cautionary tale of one Amazon team that built a working service in Rust, only to see it get rewritten from scratch in Java after a reorganization because the new team that came in couldn’t justify the payoff to learn an entirely new language.
‘Deep soul searching and dark places’
Based on Cohen’s observations of Rust adoption inside Amazon, he said it takes engineers about three months to get their bearings, with a difficult period in the middle where it gets especially hard.
“There is some deep-soul searching with the borrow checker, some dark places,” Cohen said, referring to the strict rules that Rust enforces to manage memory safely. “And this is where people either push through and learn to think in Rust, or they give up.”
For this reason, Cohen advises teams to adopt Rust only when it delivers an order-of-magnitude improvement over existing technology. A case in point was Amazon’s Fire TV team, which used Rust to cut memory usage on its devices by 10x — a big win that justified the cost.
Aaron DeVore, a software developer at Portland State University who has been attending RustConf since its early days, said part of the language’s appeal is rooted in its helpfulness. After getting a computer science degree and working through the “classic bugs” in other languages, he was accustomed to the frustration of cryptic error messages.
With a language like C++, he explained, “you type one thing wrong, and you get this page full of errors” that offers little explanation of what the problem actually is.
Rust, by contrast, is designed to guide the developer. In the Rust community, a confusing error message is considered a bug in the compiler itself. “Rust is like, oh, yeah, you probably want to change this,” DeVore said. “And here’s exactly where the error came from.”
That supportive ecosystem is now getting a more formal structure. In her opening remarks, Rebecca Rumbul, the executive director and CEO of the Rust Foundation, announced two major steps reflecting the language’s growing maturity.
- First, she announced the launch of the Rust Innovation Lab, a new program to provide a home for funded and maturing Rust projects. Its inaugural member is Rustls, a critical, memory-safe security library that focuses on cryptographic security.
- Second, she revealed that Arm had upgraded its membership to the Platinum level, a significant financial commitment at a pivotal moment for the open-source community.
With this growing corporate involvement, Rust’s long-term success may depend on its ability to manage the tension between its new backers and its passionate, open-source community.
Balancing community and corporate interests
Scott McMurray, a project director on the Rust Foundation board, said the structure provides a firewall designed to give the community “its own unique voice, distinct from the companies.”
He contrasted the needs of large corporations with those of individual enthusiasts, like one developer who’s passionate about using Rust on a handheld gaming device.
“Let me tell you, none of the big corporations care about using Rust on a Nintendo 3DS,” McMurray said — but the community structure aims to balance both worlds.
That community spirit was the focus of a keynote by Nell Shamrell-Harrington of Microsoft, the lead editor of the This Week in Rust newsletter and a Rust Foundation board member. She shared a story from 2020, when she and much of the Rust team at Mozilla were laid off, a moment that could have fractured the project. Instead, the community rallied.
“I was stunned at the outpouring of support from our community,” she recalled, describing messages from people she didn’t know offering help. “I cannot think of any other instance in my professional career where I felt so seen and I felt so supported.”
Now that Rust has achieved widespread adoption, the community faces the new challenge of deciding where to go next, explained Nicholas Matsakis, a senior principal engineer at Amazon Web Services who is also co-lead of the Rust language design team.
For years, he said, the focus was on solving developers’ problems and expanding Rust’s adoption because the project’s survival depended on it. Now, with that goal largely achieved, success itself has made the path forward less obvious and requires deeper thinking
“What is Rust’s mission in the world? I mean, are we just here to make every single program be written in Rust? Like, OK, maybe,” Matsakis said, laughing during the closing keynote.
Then he added, on a more serious note, “But hopefully not. We want to find where Rust really adds value, and double down on that.”
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