Yi 1.5 9B Chat

Yi 1.5 9B Chat is a bilingual English/Chinese instruction-tuned model from 01.AI, released May 2024 with 9 billion parameters. It targets tasks where Chinese-language fluency matters — translation, mixed-language code comments, and cross-lingual retrieval — though its 4K context ceiling is a real constraint for retrieval-augmented pipelines or long-document workflows. On MMLU it scores around 69.5, competitive for a 9B model at the time of release but now trailing Qwen 3 8B on most general benchmarks. Licensed Apache 2.0, which makes it a clean fine-tuning base; some teams still prefer it over newer alternatives specifically because of the bilingual pretraining distribution and the permissive license with no usage restrictions.