GPT-4.5

GPT-5.2

OpenAI

GPT-5.2 is OpenAI's flagship frontier model series designed for professional knowledge work, advanced coding, and agentic workflows. Released in December 2025 as a response to competitive pressures, it features a massive 400,000-token context window and a 128,000-token maximum output capacity. The model utilizes a Mixture-of-Experts (MoE) architecture to balance inference efficiency with deep reasoning capabilities. It is available in three variants—Instant, Thinking, and Pro—each optimized for different points on the latency-intelligence curve. GPT-5.2 demonstrates state-of-the-art performance in tool calling reliability (98.7%), coding (SWE-Bench Verified 80.0%), and long-context retrieval.

GPT-5.1

OpenAI

GPT-5.1 is a frontier-grade multimodal language model family released by OpenAI in November 2025. It introduces a unified system architecture featuring a 'Smart Router' that dynamically allocates compute resources between two primary modes: 'Instant' (optimized for low latency and conversational warmth) and 'Thinking' (optimized for deep, adaptive reasoning). The model utilizes a Sparse Mixture-of-Experts (MoE) architecture with a central language backbone and attachable modules, allowing it to process text, audio, image, and video inputs natively. Key capabilities include adaptive test-time compute, where the model adjusts its reasoning depth based on query complexity, and enhanced personalization options with distinct personality presets. It demonstrates significant improvements in instruction following, coding (via the Codex variants), and mathematical reasoning compared to its predecessor, GPT-5.

GPT-OSS-120B

OpenAI

GPT-OSS-120B is a state-of-the-art open-weight language model that delivers strong real-world performance at low cost. This 120 billion parameter mixture-of-experts model achieves near-parity with OpenAI o4-mini on core reasoning benchmarks while running efficiently on a single 80 GB GPU. It was trained using reinforcement learning and techniques informed by OpenAI's most advanced internal models, including o3 and other frontier systems.