Reflection previews Beam, a 501B open-weight MoE coding model with Apache 2.0 weights due this month

Beam activates 23B of its 501B parameters per token, has 1M-token context, and Reflection reports 80.9 on SWE-bench Verified and 80.1 on Terminal Bench 2.1, roughly level with GLM 5.2 at 3–4x less inference compute but behind Kimi K3 and GLM 5.3. It's waitlist-only for now, with weights, a technical report, and fine-tuning tooling promised later in October.