Today, we are pleased to share that CoreWeave has acquired Bufstream, our Apache Kafka-compatible streaming platform, from Buf. CoreWeave, a leading AI cloud, has added Bufstream to its internal platform as part of the W&B Models and Weave product lines.
When we built Bufstream, we set out to create a modern, cost-efficient alternative to Apache Kafka - one that eliminated the operational complexity of managing brokers, tiered storage, and replication. CoreWeave's platform is purpose-built for high-performance, compute-intensive workloads. Streaming data at the scale that AI and ML pipelines demand is a natural fit.
What This Means for Buf
Buf will continue to operate independently, focused on the Buf Schema Registry (BSR), Protobuf tooling, and its broader schema-driven development mission.
This transaction sharpens our focus on what we believe is most important: making schemas the source of truth.
Buf was founded on the conviction that structure is the highest-leverage investment you can make in a software system. Define your interfaces rigorously — through schemas, type-safe contracts, and validated specifications - and everything downstream improves: code generation, correctness, interoperability. The industry has been moving in this direction for years, but AI has changed the calculus entirely. When software is increasingly written and operated by AI, the bottleneck shifts from implementation to specification — the spec becomes the primary artifact, because it's the only thing you can verify. Schema-driven development is no longer a best practice for the careful. It's the foundation for systems that need to be trustworthy whether a human or an agent is at the controls.
We've spent years building the tools and standards that make this real. The Buf CLI replaced legacy Protobuf tooling across the industry. ConnectRPC is in CNCF and has become the modern alternative to legacy RPC libraries. Protovalidate is the validation standard for Protobuf. The Buf Schema Registry is the only Protobuf package manager at enterprise scale. We built the compiler, wrote the spec, and shaped the conventions the ecosystem relies on. That work is accelerating.
Schemas today define the contract between services. We've been thinking about what happens when you push that idea further - when schemas become the foundation for verifying not just individual APIs, but how your entire architecture behaves as a unit. That's where we're headed, and this transaction lets us get there faster.
What This Means for Buf Customers
Our commitment to the Buf Schema Registry, our open-source tools, and our enterprise platform is stronger than ever. This move lets us go deeper on the things our customers already rely on us for. Buf powers schema-driven development at some of the largest organizations on earth, and we're excited to keep delivering — across the platform we've built so far, and what we're building next.
