Jamsocket

Jamsocket (also referenced by its founders as Drifting in Space) was a backend platform for building sync engines and high-performance, browser-based applications. Its core idea was to give every end user of an application a dedicated, session-lived backend process — an architecture used by products such as Figma and GitHub Codespaces — and to make deploying that architecture as straightforward as deploying a conventional web server.

The company shipped several components: Plane, an open-source orchestrator that powers the Jamsocket platform; Y-Sweet, a document store and realtime sync backend running on top of Jamsocket; and ForeverVM, a service providing stateful Python REPLs for AI code execution. Jamsocket's infrastructure was built on gVisor, the secure container runtime also used by Modal.

On July 10, 2025, Modal announced that the Jamsocket team was joining Modal through an acquisition. Co-founders Paul Butler (CEO) and Taylor Baldwin (CTO) joined Modal to build Jamsocket- and ForeverVM-like functionality into Modal's platform, while existing Jamsocket products were to continue operating during migration. Y Combinator lists Jamsocket's status as acquired.

Founding story

Jamsocket was founded in 2021 by Paul Butler and Taylor Baldwin. Butler's background spans engineering and data science, including software engineering on search at Google, quantitative analysis at Two Sigma, and botnet detection at an adtech startup; he is originally from Halifax, Canada and based in Brooklyn. Baldwin was previously a software engineer at Uber and Datadog building WebGL-based data visualization applications in the browser, worked at one point with the New York Times R&D team, and holds bachelor's and master's degrees in piano performance and pedagogy.

Business model

Jamsocket sold developer infrastructure: a hosted backend platform on which application developers deployed per-user, session-lived backend processes and realtime sync services, complemented by an open-source orchestrator (Plane). The sources do not specify pricing terms.

Not specified in the available sources beyond the sale of hosted backend platform services to application developers.

Traction

Public sources provide limited traction data: a team size of 5 and Y Combinator Winter 2022 participation. Modal noted that applications built on Jamsocket were increasingly AI-centric, and that customers would gain access to GPU inference and sandboxes post-acquisition.

Latest developments

On July 10, 2025, Modal announced Jamsocket was joining the company. Paul Butler and Taylor Baldwin joined Modal's team, Jamsocket products were to keep operating while core functionality migrated to Modal, and Jamsocket web properties now redirect to the acquisition announcement.