GPT-5.6 Luna

• ⚡ Fast, cost-efficient tier of OpenAI's GPT-5.6 series
• 📏 Massive 1M-token context window
• 🧠 Capable reasoning for its price tier
• 👁️ Vision input plus function calling and web search
• 🎯 Built for high-volume, latency-sensitive workloads
• 💬 Chat, classification, lightweight agentic tasks

OpenAI

OpenAI is an American artificial intelligence research organization headquartered in San Francisco, structured as both a for-profit public benefit corporation and a nonprofit foundation. The lab developed the GPT family of large language models, the DALL-E…

GPT-5.6 Luna is the fast, cost-efficient tier of OpenAI's GPT-5.6 series, released in July 2026. It targets high-volume, latency-sensitive workloads — interactive chat, text classification, and lightweight agentic pipelines — while still offering meaningful reasoning quality for its price bracket. A one-million-token context window lets it hold entire codebases, document sets, or long conversation histories in a single pass, and it supports vision input, function calling, and web search out of the box.

Within OpenAI's lineup, Luna sits at the efficiency end of the GPT-5.6 family, distinct from the heavier reasoning tiers represented by siblings like GPT-5.6 Terra and GPT-5.6 Sol. Each of these ships alongside a "Pro" counterpart, including GPT-5.6 Luna Pro, which trades some speed for additional headroom on harder tasks.

Choose Luna when throughput, responsiveness, and cost matter more than maximum depth — customer-facing assistants, batch classification, retrieval-augmented workflows over large contexts, and tool-driven agents that need to run frequently and cheaply.