OpenAI o3

OpenAI o3 is a reasoning-focused model released in April 2025 that takes time to think before responding, enabling more deliberate and accurate problem-solving. With a 200K token context window, o3 represents OpenAI's effort to create models that can engage in deeper reasoning processes rather than simply generating immediate responses.

The model demonstrates exceptional performance on challenging benchmarks, achieving 88.9% on AIME 2025 (American Invitational Mathematics Examination) and 69.1% on SWE-bench Verified, a benchmark testing software engineering capabilities. These results highlight o3's strength in mathematical reasoning and complex code understanding tasks.

A key feature of o3 is its ability to use tools agentically, including web search, code execution, and image generation. This agentic capability allows the model to autonomously decide when and how to use external tools to solve problems, making it particularly effective for complex, multi-step tasks that require more than pure language generation.