Claude Haiku 5.5
Anthropic just quietly dropped Claude Haiku 5.5—cheaper, faster, and now handling enterprise tasks that used to need Claude 3.5 Sonnet.
Why it matters
A significant capability tier shift in the small-model category. Haiku 5.5 raises the floor for cost-sensitive deployments and agent use cases where latency matters more than raw reasoning power. Enterprise practitioners need to re-evaluate their Claude model selection matrix.
The key facts
5 to knowClaude Haiku 5.5 released (October 7, 2026)
Positioned as cheaper and faster than prior Haiku versions
Capability gains sufficient to displace Sonnet 3.5 in some workloads
Small model tier advancement—frontier capability trickling down to edge/agent inference
Source: Simon Willison personal blog (independent technical analysis, not vendor announcement)
The story so far
Earlier coverage of this storyline
- Claude Haiku 5.5 now available on AI GatewayVercel Blog
- Claude Haiku 5.5 arrives with massive price cuts proving the AI pricing arms race is far from overThe Decoder
- Introducing Claude Haiku 5.5 on AWSAWS Machine Learning Blog
- This story
Go to the source
Simon Willisonsimonwillison.net