Best Open-Source LLMs

GPT OSS 120B is OpenAI's first large open-weight language model, released August 2025. It uses a Mixture-of-Experts architecture with 117 billion total parameters and 5.1 billion active per forward pass — designed so it can run on a single H100 GPU. With an AA Intelligence Index of 33 (#1 of 50 in reasoning open-weight models), it's the most capable officially released open-weight model from a frontier lab. At $0.15/$0.60 per 1M tokens and 336 tokens/second, it's both cheap and fast. The open weights are available on Hugging Face and can be self-hosted. A smaller companion model, GPT OSS 20B, runs on consumer 16GB GPUs at $0.05/$0.20 per 1M.

DeepSeek's open-weights frontier model and one of the most cost-effective APIs available. V3.2 punches far above its price — at $0.28/$1.10 per 1M tokens it costs roughly 20× less than Claude Sonnet while delivering an AA Intelligence Index of 32. Strong on coding and reasoning tasks, but hosted in China with the privacy implications that brings.

Meta's mid-sized open-weights model and the most capable Llama 4 variant for general use. Maverick runs as a mixture-of-experts architecture with 400B total parameters but only 17B active — giving it good speed at 115 t/s while maintaining an AA Intelligence Index of 18. It's multimodal, handles 1M tokens of context, and can be self-hosted. The trade-off: it trails frontier closed models significantly on all AA-measured benchmarks.

Kimi K2 (0905) is the flagship model from Moonshot AI, a Beijing-based startup — and the current default model on T3.chat. It's a Mixture-of-Experts model with 1 trillion total parameters and 32 billion active per forward pass, released September 2025. Kimi K2 scores an AA Intelligence Index of 31 (#6 of 36 in open-weights large models) and is available as open weights under a permissive license. At $0.39/$1.90 per 1M tokens via the Moonshot API with a 262K context window, it offers strong capability per dollar. Also available in a dedicated Thinking mode for complex reasoning. A newer version (Kimi K2.5) has since launched.

Meta's ultra-long-context open-weights model with a 10M token window — the largest of any publicly available model. Scout is a smaller MoE variant (109B total, ~17B active) optimized for speed and context length over raw intelligence. At 135 t/s and AA Intelligence Index 14, it's the right call when you need to process enormous documents or codebases that would overflow any other model.

Qwen 3 235B is Alibaba's largest open-source language model, released April 2025 under the MIT license. It uses a Mixture-of-Experts architecture with 235 billion total parameters and 22 billion active per forward pass. With a 262K context window and pricing as low as $0.20/$0.88 per 1M tokens on Alibaba Cloud, it's one of the most capable open models available at scale. Qwen 3 235B supports both a standard instruct mode and a Thinking mode for step-by-step reasoning. AA Intelligence Index of 17 reflects its April 2025 release date — newer open models have since surpassed it. A newer Qwen3 235B 2507 version has been released for those wanting the latest.