s2.dev
s2.dev is a YC Fall 2025 (F25) company. Based in San Francisco, CA, USA. Team of 5.
About s2.dev
Summary
s2.dev builds a serverless API for durable, real-time streams, giving developers a cloud storage primitive for moving data the way object storage handles static data. Engineers use it to persist and read ordered, append-only streams at unlimited scale without managing clusters or brokers. It replaces self-hosted Kafka setups and ad-hoc log infrastructure for use cases like agent coordination, real-time data broadcasting, and multiplayer sync.
Business model
Pay-per-use based on append and read operations, with a self-hostable open-source tier (s2-lite) and a managed cloud offering.
Go-to-market
Developer-led adoption through a self-serve playground, CLI, and SDKs for TypeScript, Go, Rust, and Python, targeting backend engineers and platform teams who discover the product directly via docs and open-source tooling.
From the Y Combinator listing
API for unlimited, durable, real-time streams
S2 is a serverless datastore for real-time, streaming data. The more we worked on data systems, the more we felt like there was a missing building block. The seamless experience of object storage simply did not exist for durable streams – so we set out to fix that! S2 reimagines streams as an unlimited and access-controlled web resource. Like if Kafka and S3 had a baby. - Building agents? Use granular streams to persist context in real time, make workflows auditable, and coordinate between agents. - Publishing fast-moving data? Streams support high fanout and can be accessed directly over the internet, so they are a great fit for broadcasting real-time feeds. - Sandboxing? Emit to per-instance streams, and read history or live events just as easily. - Local-first and multiplayer experiences? Propagate updates reliably and efficiently. Stop dealing with clusters, and start streaming.
Facts
- B2B / B2B -> Infrastructure
- San Francisco, CA, USA
- 5
- Active
- Early
Founders (3)
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