Compare AI Models Side by Side

GPT-5.6 Sol: Flagship of OpenAI's GPT-5.6 family (Sol/Terra/Luna tiers), announced as a limited preview Jun 26 2026 with general availability Jul 9 2026. Strong on long-horizon, command-line, and multi-step coding tasks. On the independent ARC-AGI-3 public set, OpenAI reported the official-harness score understates it: enabling retained reasoning and compaction lifted the result from 13.3% to 38.3%, beating Claude Opus 5's 30.2% on the same set — a real, reproducible optimization rather than a benchmark discrepancy, but flagged here since the two settings are not on by default. API identifier gpt-5.6-sol, knowledge cutoff Feb 16 2026. Superseded as OpenAI's flagship by GPT-6 Astra (Sep 3 2026).

GPT-6 Astra: Ships with web search, code interpreter, a hosted shell, apply-patch, computer use, and MCP support built in. Staged rollout starting with a limited partner preview Sep 3 2026, then ChatGPT Plus/Pro/Business/Enterprise plus the API and AWS over the following days. First OpenAI model to hit the 'Critical' cybersecurity threshold under the company's own Preparedness Framework; its most advanced cyber capabilities are gated behind the enterprise-only 'Daybreak' program rather than shipped broadly. Fortune reported OpenAI quietly revised some evaluation metrics upward after a delayed publication of the launch announcement, a credibility flag independent of the ARC-AGI-3 discrepancy above. Strongest, most independently-corroborated advantage across hands-on reviews is cost/token efficiency on agentic coding and robotics tasks rather than raw intelligence; the cross-vendor Artificial Analysis index and Humanity's Last Exam both still favor Claude Fable 5.1 and Opus 5. API identifier gpt-6-astra, knowledge cutoff Apr 30 2026.