Claude Sonnet 5.5 (Adaptive Reasoning, Max Effort, Default Fallback) debuts at #2
Claude Sonnet 5.5 is a model from Anthropic, released on 28 Sep 2026. First seen 28 Sep 2026. Catalogues list a 1,000,000 tokens context window. 18 evidence links.
Facts as of
- Context window
- 1,000,000
- Input · USD / 1M tokens
- $2.00
- Output · USD / 1M tokens
- $10.00
- Max output
- 128,000
- Input
- text · image
- Output
- text
- Cached input · USD / 1M tokens
- $0.10
Alex's take
Evidence links 18
- Claude Code · model idsevidence linknpmjs.com
- Anthropic APIevidence linkdocs.anthropic.com
- Vertex AI · Model Gardenevidence linkconsole.cloud.google.com
- Anthropic · site pagesevidence linkanthropic.com
- OpenRouterevidence linkopenrouter.ai
- Vercel AI Gatewayevidence linkvercel.com
- Anthropic · deprecationsevidence linkplatform.claude.com
- OpenRouterevidence linkopenrouter.ai
- OpenCode · discoveryevidence linkopencode.ai
- Artificial Analysis · benchmarksevidence linkartificialanalysis.ai
- OpenCode Zen · modelsevidence linkopencode.ai
- Command Code · modelsevidence linkcommandcode.ai
- Claude Docsevidence linkplatform.claude.com
- DesignArena · uicomponentevidence linkdesignarena.ai
- DesignArena · websiteevidence linkdesignarena.ai
- Anthropic · API pricingevidence linkplatform.claude.com
- models.dev · catalogueevidence linkmodels.dev
- models.dev · catalogueevidence linkmodels.dev
Related signals
AnthropicSightingClaude Haiku 5.5 (Max, Default Fallback) enters at 43.4 on the Intelligence Index
Confirmed20 evidence links