Starting September 30 at 8am PT, Arena.ai will make Anthropic’s Claude Sonnet 5.5 available for direct testing. Claude Sonnet 5.5 (High) stays in Direct Mode for 48 hours and remains in Battle and Agent Mode afterward.
Arena.ai says OpenAI’s GPT-6.1 can now be tested in Agent Arena, where scores are still to come, and in Code Arena for WebDev, Text, Vision, Search, and Document. OpenAI says GPT-6.1 Sol offers near-Astra intelligence for a fifth of the price.
Arena.ai compared 34,580 verdicts from 12 models with human votes across 1,460 Arena battles. On average, a model chose its own answer 58% of the time, while people chose that same answer 34% of the time.
OpenAI’s GPT-6 Sol (Medium) can be selected in Arena Direct Mode for the next 24 hours, through Sept. 29 at 9am PT. Arena.ai says it will remain available in Battle and Agent Mode after that window.
The new overview gathers live signals on newly added models, category performance, capability notes, and Arena news, and can show cross-arena scores for models such as GPT-6 Sol and Claude Opus 5.5.
Tenure-track faculty at U.S. universities can submit Fall 2026 proposals on the scientific foundations of AI evaluation. Each project may receive up to $50,000, and the deadline is October 30, 2026.
Arena.ai says it has generated side-by-side outputs from Anthropic’s Claude Opus 5.5 and OpenAI’s GPT-6 Sol, and that scores for Claude Opus 5.5 are coming soon.
Arena.ai reports that OpenAI’s GPT-6 Sol (Max) scored 1,689 points and placed fourth in Code Arena: WebDev, at a blended price of $8 per million tokens. It is 72 points above GPT-5.6 Sol (xHigh), while Arena.ai says GPT-6 Luna’s score is still pending.
On Arena.ai, both models can be tried in Battle Mode and Agent Mode.
Arena.ai has added Claude Opus 5.5 to Agent Arena and to Battle Mode for WebDev, Text, Vision, and Document. Claude says it is the first Claude 5.5 model, performs at the level of Claude Fable 5.1 for most tasks, and costs 40% less to run than Opus 5.
