Jason Warner is co-founder and co-chief executive of Poolside, which develops foundation models and autonomous tools for software engineering. Previously GitHub’s chief technology officer, he helped bring GitHub Actions, GitHub Codespaces, and GitHub Copilot to market before founding a company premised on software development as a route to artificial general intelligence.
Warner began programming during a high-school placement at IBM in Connecticut. He earned a computer science degree from Penn State and a master’s degree from Rensselaer Polytechnic Institute, then worked on Ubuntu desktop and phone products at Canonical and became vice president of engineering at Heroku.
He joined GitHub in 2017, helping expand it from collaborative code hosting into a broader development platform encompassing automation, cloud development, security, and AI-assisted coding. After leaving in 2021, he became a managing director at Redpoint Ventures, where he and Eiso Kant incubated Poolside before founding it in 2023. Their partnership grew out of Warner’s unsuccessful attempt to acquire Kant’s earlier coding-completion company while at GitHub. Warner also serves on Atlassian’s board.
The technical bets behind Poolside
- Software as a route to general intelligence. Warner treats programming as an unusually useful training environment because execution, compilation, and tests turn proposed answers into observable outcomes. The ambition extends beyond code completion toward systems capable of sustained, economically useful work.
- Reinforcement Learning from Code Execution Feedback. Poolside combines foundation-model training with feedback from running candidate programs. This approach, called RLCEF, uses real execution results to improve coding and reasoning instead of judging outputs solely by whether they resemble existing code.
- Governed coding agents. Warner emphasizes that agents working with enterprise, government, and defense software require constrained permissions, human oversight, and protected customer environments. Poolside’s AWS partnership supports customer-controlled deployment, including on-premises and air-gapped installations. In a joint demonstration with Kant, an agent translated Ada software into Rust, ran builds and tests, and added command-history functionality.
- Open-weight coding models. In April 2026, Poolside introduced Laguna XS.2 and Laguna M.1, a terminal coding agent, and the Shimmer development environment. Laguna XS.2 ships under Apache 2.0 and can run on a single GPU; Laguna M.1 also has publicly available weights.
