Claude Haiku 4.5 (latest)

Claude Haiku 4.5 is Anthropic's lightest-weight current member of the Claude family, positioned in the official comparison table as the "Fastest" latency tier alongside higher-priced siblings like Sonnet the listed price, Opus 5.5, and Fable 5.1. It ships with an "Extended" thinking configuration that enables deeper reasoning behavior on demand, while keeping response times minimal for high-throughput scenarios such as real-time assistants, large-scale classification, and embedded agentic workflows where the per-token economics of larger Claude tiers would be impractical.

In practice, Haiku 4.5 is intended for teams who need Claude-quality reasoning at the lowest cost and latency in the lineup, making it well suited for tool-calling pipelines, retrieval-heavy applications, and latency-sensitive customer-facing features. Its placement beneath the Sonnet, Opus, and Fable tiers in the comparison table signals a deliberate trade-off in favor of speed and affordability over the larger context window and higher output ceilings of the more capable Claude models.