GPT-5.6 Sol (Official API)

GPT-5.6 Sol sits inside the gpt-sol family and is positioned as a flagship OpenAI model for agent-style workloads that combine reasoning with multimodal input. According to OpenAI's own pricing communications, the official API and ChatGPT Work / Codex credit pricing for GPT-5.6 Sol was cut by more than 20% on August 21–22, 2026, setting the standard published rate at $4 per million input tokens and $20 per million output tokens for at least three months, with promotional pricing guaranteed through November 21, 2026. That price card applies to direct OpenAI API usage, while subscription tiers such as Pro, Plus, and Business remained unchanged, so the discount is most meaningful for developers and teams running token-metered workloads rather than consumer chat subscribers.

The model's design emphasis, as reflected in its capability profile, is on structured, tool-driven reasoning over text, image, and PDF inputs with text-only outputs, making it a fit for retrieval-augmented agents, document understanding pipelines, and long-context analysis where the 271,999-token window and 128,000-token output ceiling matter. The temporary official price cut materially improves its cost economics against rival frontier APIs on paper, which broadens its appeal for high-volume agentic loops where every million tokens compounds. For practitioners, GPT-5.6 Sol is best suited to production agent harnesses that want a stable, officially supported OpenAI backbone with multimodal grounding, structured output, and tool calling, while keeping an eye on the November 2026 pricing horizon when promotional rates are scheduled to expire.