Reflection releases open weights for Beam, its 501 billion parameter coding and agent model, under Apache 2.0 with 40 plus partners
Beam is now available across platforms, with open weights under the Apache 2.0 license - in collaboration with an ecosystem of 40+ partners. We're releasing: - Weights, tokenizer, and reference implementation - BF16, FP8 and NVFP4 weights and a DFlash2 drafter - The open source harness we built and trained Beam on: Mirror CLI Weights and model card on Hugging Face:
Context
A large US open weight model under a permissive license gives companies another frontier class option they can run and customize on their own hardware.
This is a first hand release post from Reflection. Beam was already named in benchmark comparisons earlier this week, so this post marks the open weights becoming broadly available rather than the model's first appearance.
Deep dive
On October 16, Reflection posted that Beam is now available across platforms with open weights under the Apache 2.0 license, in collaboration with more than 40 partners. It said it is releasing the weights, tokenizer and reference implementation, BF16, FP8 and NVFP4 weights with a DFlash2 drafter for faster decoding, and Mirror CLI, the open source harness it built and trained Beam on.
The Hugging Face model card describes Beam as a text only mixture of experts model with 501 billion total and about 23 billion active parameters, a 1 million token context window and a June 30, 2026 knowledge cutoff, built mainly for English software engineering, reasoning and agent work. Reflection's blog says the model card includes final benchmarks and that a safety technical report describes its evaluations.
Reflection lists launch platforms including AWS, Google Cloud, Microsoft Azure, CoreWeave, Databricks, Fireworks AI, Together AI, OpenRouter, Ollama and Nvidia NIM. Hugging Face says Beam has day zero support in Transformers, vLLM and SGLang, with fine tuning recipes.
Meta's benchmark table for Muse Spark Open on October 15 included Beam as one of the comparison models.
What to expect next
Watch independent benchmarks comparing Beam with Muse Spark Open, Kimi K3 and other open models on coding and agent tasks.
Also watch whether companies adopt Beam for self hosted coding agents given its permissive license, how Mirror CLI compares with other harnesses, and whether Reflection follows with smaller or multimodal versions. Download counts on Hugging Face will give an early read on uptake.