Reflection Releases Beam, a 501B-Parameter Open-Weight Model, Under Apache 2.0

Reflection released the weights for Beam, its first open-weight model, on October 16, 2026. The model is on Hugging Face under the Apache 2.0 license, which lets companies use, modify and redistribute it, alongside a model card and a safety technical report. Reflection first announced Beam on October 5 and said then that it was undergoing final red-teaming before the weights went out.

What Beam is

Beam is a sparse mixture-of-experts model with 501 billion total parameters, of which about 23 billion are active for each token. According to the model card it has 52 layers, 256 experts per mixture-of-experts layer, and a 1-million-token context window. It takes text in and produces text out, was developed predominantly for English, and has a knowledge cutoff of June 30, 2026. Reflection is releasing the weights in BF16, FP8 and NVFP4 precision, plus a smaller drafter model for speculative decoding.

How it was trained

Reflection says Beam was pretrained on 23.8 trillion tokens from the web and licensed datasets. Its main reinforcement-learning run generated more than 100 million rollouts on 10,500 NVIDIA GB300 GPUs over four weeks, and across RL training, evaluation and ablations the company says it ran roughly 1.3 billion sandboxes.

How it scores

On Reflection’s final model card, the BF16 version scores 81.6% on SWE-bench Verified, a test built from real GitHub issues, plus 80.1% on Terminal-Bench v2.1, 97.7% on AIME 2026 and 90.6% on GPQA Diamond. These are Reflection’s own numbers. The company says Beam is competitive with GLM 5.2 and approaching Qwen 3.8-Max on coding and agentic tasks, while open models such as Kimi K3 remain ahead on raw capability; it pitches Beam’s advantage as efficiency at inference time.

Where you can run it

Beam launches with more than 40 partners and integrations, including Amazon Web Services, Google Cloud, Microsoft Azure, Hugging Face, Together AI, OpenRouter and NVIDIA NIM, with Dell and HPE offering on-premises and air-gapped deployments. Reflection also open-sourced Mirror, a command-line coding agent it trained Beam alongside, and says Beam works with other harnesses such as OpenCode and Hermes. A free public beta of Reflection’s own API is open now.