GPT-5.6 Sol Pro

• 🧠 Flagship GPT-5.6 Sol served with reasoning mode set to pro.
• 📏 Context window of about one million tokens for long-horizon work.
• 🆕 Introduces new maximum reasoning effort and subagent-driven ultra mode.
• 🔧 Tuned for agentic coding, command-line tasks, and multi-step reasoning.
• 👁️ Multimodal capabilities: vision, function calling, and web search.
• 🎯 Reasoning-heavy tier prioritizing response quality over speed.
• 🏢 OpenAI preview model, initially limited to trusted partners.
• 🔒 Layered safety measures accompany the limited preview release.

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 Sol Pro is not a distinct model but the flagship GPT-5.6 Sol served with its reasoning mode set to "pro," which allocates more deliberation for higher-quality responses on complex tasks. Sol sits at the top of OpenAI's GPT-5.6 lineup, roughly corresponding to the unsuffixed flagship tier in earlier GPT-5 releases, and is aimed at demanding agentic coding and long-horizon reasoning workloads. It shares the family with GPT-5.6 Sol, the GPT-5.6 Terra tier, and the GPT-5.6 Luna tier, plus their respective Pro variants.

Compared with the earlier flagship line, notably GPT-5.5 and GPT-5.5 Pro, the GPT-5.6 generation introduces a new maximum reasoning effort setting that gives the model more time to reason deeply, along with an ultra mode that uses subagents to parallelize complex multi-step work. OpenAI describes Sol as particularly strong at command-line and multi-step coding and long-horizon problem solving.

Like the rest of the GPT-5.6 family, Sol Pro carries a roughly one-million-token context window and supports vision, function calling, and web search alongside its reasoning capabilities.

At release, GPT-5.6 was a limited preview restricted to trusted partners rather than broadly available, and OpenAI paired the rollout with additional safety measures during the preview period.