Anthropic Claude Sonnet 5.5, released in September 2026, is the new-generation mid-tier model offering the best combination of speed and intelligence, positioned as a faster, more economical companion to Opus 5.5 for well-scoped everyday tasks, bug fixing, and polished documents. Against Sonnet 5 it generates output more than 30 percent faster and needs less work to finish the same task; agentic coding on Terminal-Bench jumps from about 10 to 70 percent, knowledge work nearly matches Opus 5.5, and computer use and chart reading improve markedly. Its knowledge cutoff is June 2026, and it supports very long context for processing many documents at once. The interface offers a reasoning-effort dropdown (five levels, default high), an option to show the thinking process, web search, and image and document upload. A strong everyday default; use Opus 5.5 for the hardest reasoning and Haiku 5.5 for light, low-latency chat. If you need to search the web for information, please turn on the "Web Search" switch. Maximum context window (input and output combined): about 1,000,000 tokens. Maximum output per reply: about 64,000 tokens (model reasoning, if any, counts toward this limit). Maximum total upload size per request: 512MB (all files and message content combined). Accepted document formats: pdf, docx, xlsx, pptx, txt, csv (file content is provided to the model as extracted text). Accepted image formats: gif, jpeg, jpg, png, webp. Animated GIF images are analyzed using only the first frame. Maximum number of images: 600. When uploading more than 20 images, each side must be at most 2,000 pixels. Maximum size per image: 10MB (base64-encoded). Maximum total image size per message: 20MB (text and history share the same request size limit; uploads close to the limit may still be rejected). Image dimensions: 200 to 8,000 pixels per side. Output content formats: Text/Image Pricing: Medium-high This module supports continuous conversations. AI can make mistakes. Please verify important information.