OpenAI: GPT-5.6 Luna

GPT-5.6 Luna is a commercial OpenAI model that accepts text, image, and file inputs. Its context window is 1,050,000 tokens, and a single response can run up to 128,000 tokens, which leaves room for long documents or large file sets in one request. It supports tool calling and reasoning. The listing does not confirm structured output support, so anyone who needs schema-constrained responses should verify that separately. At $0.20 per million input tokens and $1.20 per million output tokens, it belongs on the shortlist for teams processing high volumes of long-context or multimodal input on a tight budget. Its blended benchmark score of 62.3 rests on just one independent benchmark, an AI index score of 61.6, so its standing is thinly evidenced. Treat that number as a starting signal rather than proof, and test the model on your own workloads before committing.