DeepSeek Releases Open-Weight V4.1-Flash-1017, Claims Code Benchmark Lead Over Claude Opus 5

DeepSeek released its AI model DeepSeek-V4.1-Flash-1017 on October 17, 2026, making the model weights available for free on Hugging Face under the MIT license on the same day, permitting commercial use, modification, and redistribution. The model is a minor update to V4.1-Flash released in September, supporting text and image inputs with a context length of 1 million tokens.

According to benchmark results published by DeepSeek, the new model outperformed Anthropic's top-tier paid model Claude Opus 5 in four metrics: scoring 77.0 on the code repair benchmark DeepSWE v1.1 (vs 74.0 for Opus 5), 60.5 on the business automation benchmark Automation-Bench v1.0.6 (vs 50.3), 35.4 on Agents' Last Exam (vs 28.6), and 72.1 on Apex Bench v1.1 (vs 65.8). These results are vendor self-reported and have not been independently reproduced.

Despite strong performance in some tasks, the model scored 42.3 on Terminal-Bench 4.0, which involves terminal-based coding, still trailing Opus 5's 51.8. It also significantly lagged behind Opus 5 on the difficult exam HLE, scoring 42.6 against 56.3. The model uses a Mixture-of-Experts (MoE) architecture with 552B total parameters, activating 8B during input and 16B during output, and includes a 196B parameter conditional memory module called Engram.