Updated September 28, 2026
What is Largest context window?
In short
The biggest prompt an AI model accepts in one request, measured in tokens.
A context window is the amount of text a model can read and answer within one request, counted in tokens. The largest one sets your ceiling for long documents, big codebases and long conversation history. AI/ML API lists 1,050,000 as its largest. Alibaba Cloud DashScope (Qwen) and Anthropic both reach 1,000,000 and 1,000,000, while Amazon Web Services lists 300,000 and AI21 Labs 256,000. A bigger window removes chunking work, but cost and latency usually scale with the tokens you send.
Sources
- aimlapi.com, checked September 26, 2026
- aws.amazon.com, checked September 26, 2026
- docs.ai21.com, checked September 26, 2026
- help.aliyun.com, checked September 26, 2026
- platform.claude.com, checked September 26, 2026