Perplexity Sonar vs Claude Fable 5.1

Perplexity’s search model is the only one that runs a web search on every single request. Sonar is built to answer questions with citations, not to reason or write code. It formulates the query, retrieves sources, evaluates them, and synthesizes a cited answer in one pass. Fast, cheap, and factual. A specialist rather than a general-purpose model, and it should be judged as one.

Anthropic's most capable generally available model, sitting above the Opus line. Fable 5.1 is built for long, unsupervised work: multi-day coding, agentic research, and tasks that run across dozens of tool calls. It reads text and images, maintains a very large context, and reasons before every answer at an adjustable depth. Its knowledge is the most recent of any Claude model. Anthropic positions Opus 5 as the starting point for most work, and Fable 5.1 for teams whose evaluations demand a higher ceiling.