Poolside

Poolside is a San Francisco- and Paris-based lab founded in early 2023 by Jason Warner (CEO, former CTO of GitHub) and Eiso Kant (CTO). Unlike the general-purpose foundation-model labs in the index, Poolside is a pure-play agentic-coding lab: it trains models from scratch for software engineering and deploys them inside customer environments (largely Global 2000 enterprises and public-sector agencies), served through its own "pool" agent harness.

Its Laguna models are Mixture-of-Experts transformers trained entirely in-house on a proprietary "Titan" stack — >30T tokens on up to 6,144 NVIDIA H200 GPUs, with a "Model Factory" pipeline (the AutoMixer data-mixture optimizer, Muon optimization, and an asynchronous online-RL system using a CISPO objective on verifiable coding rewards). In June 2026 Poolside made open weights its default: both the 33B/3B Laguna XS.2 (April 2026) and the 225B/23B flagship Laguna M.1 are now released under Apache 2.0 on Hugging Face, with base and post-trained checkpoints.

The technical execution arrives against serious company-level headwinds. In early April 2026 Poolside's planned ~$2B Series C at a ~$14B valuation — anchored by a reported up-to-$1B NVIDIA commitment — collapsed after CoreWeave walked away from its 15-year anchor lease for Project Horizon, a planned 2 GW Texas data center, when Poolside missed timelines on the first cluster. The Financial Times reported investor concerns that Poolside "could not credibly train models that compete with Anthropic, OpenAI, and Google DeepMind at the frontier." The last realized valuation is the $3B Series B (October 2024).

Note: as of June 2026, Poolside is not tracked by Artificial Analysis — benchmark numbers on these pages are self-reported from the Laguna technical report.