AI is churning out more code than ever, and engineering teams are feeling the strain. Dependencies break without warning, environments drift, and developers lose hours setting up systems instead of building features. The infrastructure that supports modern software wasn’t built for this scale, and the cracks are showing.
Flox, a startup aiming to rebuild the foundation, announced today it has raised a $25 million Series B round led by Addition, with participation from NEA, the D. E. Shaw group, Hetz Ventures, and Illuminate Financial. The fresh capital will fuel product development and help the company push deeper into enterprise markets as demand for reliable, standardized environments accelerates.
Flox’s approach centers on making Nix—the open-source technology behind one of the world’s largest package repositories—usable for teams of any size. The platform delivers consistent, portable environments across operating systems, languages, and architectures, reducing friction that plagues traditional setups.
“The extreme pressure on engineering teams has made standardized development infrastructure a necessity,” said Ron Efroni, CEO and co-founder of Flox. “While everyone else is building on top of broken foundations, Flox is strengthening the foundation itself, enabling teams to move faster without sacrificing trust.”
Since launching Flox 1.0 in March 2024, the company has rolled out more than 40 releases and landed customers ranging from Fortune 5 giants to fast-growing tech firms like Arcesium, Fellow.ai, Neo4j, PostHog, and Weaviate. Retention sits at 70%, with adoption spreading from individual developers to enterprise-wide deployments.
For PostHog, the benefits are immediate. “Flox takes the friction out of onboarding PostHog team members and contributors. Before, our local dev guide comprised 16 steps with 14 caveats. Now, it’s just a universal flox activate,” said Michael Matloka, senior product engineer at PostHog.
Kelsey Hightower, Flox advisor and longtime Google engineer, puts it more bluntly: “Flox takes the power of Nix and makes it accessible for all. That’s why we’re seeing an influx of engagement compared to traditional developer tools; they’re solving the hidden infrastructure crisis every company faces.”
With $25M in Fresh Funding, Flox Brings Nix-Powered Development to Enterprises
The Series B will be directed toward three focus areas. First, building a universal development infrastructure to make cross-OS, cross-architecture, and cross-language compatibility a standard rather than a headache. Second, automating compliance and policy management for enterprises that need governance frameworks as code volume grows. And third, delivering zero-CVE security with real-time vulnerability detection, SBOMs, and SLSA compliance—addressing risks buried in both human- and AI-generated code.
Hiring is also a priority. Flox plans to double its engineering and go-to-market teams to keep pace with customer demand and broaden its enterprise reach.
“Flox embodies the foundational transformation required for the next era of AI-driven, reliable software development,” said Todd Arfman, Partner at Addition. “Instead of patching over problems with disconnected solutions, Flox delivers a comprehensive infrastructure platform that gives engineering teams unprecedented control and visibility at the most granular level. This is the kind of deep innovation the industry urgently needs and we are proud to be partnered with the Flox team.”
Flox’s platform goes far beyond streamlining onboarding. Its package catalog, now exceeding 150,000 entries, gives teams molecular-level visibility into dependencies. Developers can standardize environments across the entire organization, roll back instantly from failures, and move beyond container limitations with reproducible, portable configurations. Native integrations with CI/CD tools like GitHub Actions and CircleCI further reduce friction.
The company has also been selected as one of a handful of authorized vendors to distribute prebuilt CUDA binaries, slashing GPU build times from hours to minutes and giving developers near-instant access to AI infrastructure.
Founded in 2021 as a spinout from the D. E. Shaw group, Flox is positioning itself as the infrastructure layer for an era when software supply chains are stretched thin by complexity and AI-driven scale. For companies wrestling with broken setups and hidden security risks, Flox is pitching itself not as a patch, but as the foundation.