A city government just out-benchmarked one of the most talked-about AI labs on the planet. Rio de Janeiro’s municipal IT company, IplanRIO, released a 397 billion parameter AI model that scored higher than DeepSeek V4 Pro on a key benchmark, and it did so by building on top of Alibaba’s open-source foundation rather than training anything from scratch.
The model, called Rio 3.5 Open 397B, went live on Hugging Face on June 13 under an MIT license. It scored 70.8 on Terminal-Bench 2.1, compared to 67.9 for DeepSeek V4 Pro and 52.5 for the base Qwen model it was derived from.
How a city government built a top-tier AI model
Rio 3.5 is a fine-tuned version of Alibaba’s Qwen 3.5-397B-A17B, which uses a Mixture-of-Experts architecture. The model has 397 billion total parameters, but only 17 billion are active at any given time.
The model also integrates what IplanRIO calls the SwiReasoning inference framework, and supports a 1 million token context window.
