Comparison · Updated Jul 27, 2026
GPT-5 vs Claude Sonnet 4.5
GPT-5 and Claude Sonnet 4.5 target similar frontier assistant workloads but differ on context length, coding posture and agentic tooling.
Model A
GPT-5
OpenAI's next-generation flagship model succeeding GPT-4o.
Aug 7, 2025
Model B
Claude Sonnet 4.5
Anthropic's coding- and agent-focused flagship in the Claude 4 family.
Sep 29, 2025
Differences
| Attribute | GPT-5 | Claude Sonnet 4.5 |
|---|---|---|
| Best at | General reasoning, multimodal chat | Agentic coding, computer use |
| Context window | 400K | 200K |
| Open source | No | No |
Analysis
GPT-5 leans on OpenAI's reasoning stack and unified multimodal I/O, while Claude Sonnet 4.5 is tuned aggressively for coding and long-horizon agent workflows including Anthropic's computer-use capability. Choice usually comes down to ecosystem: OpenAI API and ChatGPT integrations versus Anthropic's API, Bedrock and Vertex availability.