Beam: Reflection's 501B open-weight model
Reflection introduced Beam, a 501-billion-parameter open-weight model for coding and agents.
Reflection introduced Beam, its first open-weight model: a sparse mixture-of-experts with 501 billion total parameters and 23 billion active, aimed at coding, reasoning, and agentic workloads. It was pretrained on 23.8 trillion tokens and refined with reinforcement learning that produced more than 100 million rollouts on 10.5K NVIDIA GB300 GPUs over four weeks. Reflection says Beam is competitive with GLM 5.2 and approaches Qwen 3.8-Max on coding and agentic tasks while using less inference compute. Weights, a technical report, and a model card are planned later this month after final red-teaming.
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