Comprehensive side-by-side LLM comparison
Both models show comparable benchmark performance. Claude Sonnet 4.5 is available on 3 providers. Both models have their strengths depending on your specific coding needs.
Anthropic
Claude Sonnet 4.5, released by Anthropic in September 2025, is a large language model from the Claude 4.5 family that balances response quality and efficiency for coding, agentic tasks, and analytical work. It features a 200K token context window (extendable to 1M tokens in beta), 64K maximum output tokens, native image understanding, and extended thinking support. Sonnet 4.5 targets use cases that require a balance of throughput and reasoning depth, including code generation, data analysis, and multi-step agentic pipelines.
OpenAI
GPT-5.1 Instant, released by OpenAI in November 2025, is a low-latency variant from the GPT-5.1 family optimized for fast response times and high-throughput workloads. It targets real-time applications, conversational assistants, and production APIs where response speed is a primary requirement alongside GPT-5.1-generation reasoning quality.
1 month newer

Claude Sonnet 4.5
Anthropic
2025-09-29

GPT-5.1 Instant
OpenAI
2025-11
Context window and performance specifications
Average performance across 1 common benchmarks
Claude Sonnet 4.5
GPT-5.1 Instant
Performance comparison across key benchmark categories
Claude Sonnet 4.5
GPT-5.1 Instant
Claude Sonnet 4.5
2025-01
Available providers and their performance metrics
Claude Sonnet 4.5
Anthropic
AWS Bedrock
Google Cloud Vertex AI
GPT-5.1 Instant
Claude Sonnet 4.5
GPT-5.1 Instant
Claude Sonnet 4.5
GPT-5.1 Instant