From what my AIs tell me, Particle-1 is post-trained on DeepSeek V4.1 Flash 1017 which is important. It's also said to be open weight and I see Particle AI[0] on Hugging Face but no published models.

[0] https://huggingface.co/ParticleAI

A terrible slopped website. They could have put a bit more effort into an actual design.

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