Flox Secures $25M Series B to Expand Software Development Platform Built on Nix Technology

Flox has closed a $25 million Series B funding round led by Addition, bringing the company's total funding to more than $50 million. The investment will fuel three core initiatives: universal development infrastructure providing cross-OS, cross-architecture, and cross-language consistency; compliance and policy management with automated guardrails for software governance; and zero-CVE security infrastructure with real-time vulnerability detection and deep transparency into software composition.

The company's platform addresses what CEO Ron Efroni identified as the fundamental problem in software development during his tenure at Meta, where he led developer infrastructure used by more than 20,000 engineers. While his team successfully reduced build times from 40 minutes to 30 seconds, the deeper realization was that performance wasn't the core issue—consistency was. Software behaved differently from one machine to another, creating the persistent works on my machine problem that plagues development teams.

Flox builds on Nix technology, leveraging one of the largest package repositories available with immediate access to tens of thousands of pre-built, tested packages. The platform provides teams with a catalog of more than 150,000 packages, ensuring environments remain deterministic across laptops, CI systems, and production servers. This approach differs from most competitive tools that attempt to fix compatibility and security problems after they appear, while Flox prevents them by making environments reproducible and traceable by design.

Since launching Flox 1.0 in March 2024, the company has shipped over 40 releases and now serves hundreds of organizations, with more than 1,600 companies using the underlying Nix technology. Early adopters range from Fortune 5 companies to fast-growing teams like Arcesium, Fellow.ai, Neo4j, PostHog, and Weaviate. The common adoption pattern involves organic spread as developers discover the platform removes friction from their workflows.

At KubeCon NA 2025, Flox announced Kubernetes, Uncontained technology that enables teams to deploy reproducible workloads without pulling or rebuilding container images. This approach allows teams to define applications as immutable, versioned Flox environments and deploy only what the workload needs, ensuring the exact same environment used in development runs in production. The technology eliminates multi-gigabyte image pushes and unnecessary registry traffic by leveraging hash-pinned dependencies that make releases reproducible and auditable.

The platform's supply-chain security features include private catalogs, versioned environments, and instant rollbacks. It also offers native CI/CD integrations with platforms like GitHub Actions and CircleCI for automation, along with custom builds and packaging that remain reproducible, secure, and portable. The inclusion of pre-built NVIDIA CUDA packages enables teams to assemble reproducible CUDA environments in minutes and deploy them unchanged across different systems.

Flox is particularly relevant in the context of the AI coding revolution, where AI accelerates code creation but magnifies infrastructure inconsistency problems. The company is building the foundation that both human-generated and AI-generated code can rely on, ensuring that AI agents don't encounter the works on my machine problem at machine speed. With deterministic infrastructure, teams can move faster on AI applications without sacrificing reproducibility or traceability, addressing what Efroni describes as the shaky ground that current development practices sit upon.