GPT-3.5

GPT-3.5, first seen March 3, 2026, is OpenAI's unannounced large language model with a non-equivalent transitional architecture, also designated GPT-5.5. It appears without a technical report, raising questions about its capabilities and safety. The model competes directly with a dense cluster of rivals: Claude Mythos, Claude Mythos Preview, Claude 3.5 Opus, Claude Opus 4.6, Claude Opus 4.7, Gemini Flash, Gemini 3 Pro, GPT-5.3, Composer 2, Microsoft Excel, and Artificial Analysis. This broad competitive set spans AI models, productivity tools, and evaluation platforms. GPT-3.5 relies on Codex 5.3, indicating a code-generation dependency. It is also regulated by the UK AI Safety Institute and used by ExploitBench, a security testing product. With only one mention in the last 30 days and zero in the last seven, GPT-3.5 has low current visibility despite its strategic positioning.

• ·GPT-3.5 is a transitional architecture (also called GPT-5.5) with no public technical report.
• ·Competes with 11 entities across AI models, productivity tools, and evaluation platforms.
• ·Dependent on Codex 5.3 for code generation capabilities.
• ·Regulated by UK AI Safety Institute and used by ExploitBench for security testing.
• ·Near-zero recent mentions suggest limited market traction or intentional stealth.