GPT-5.5
OpenAI · April 2026
● activeClosedmixture of expertsmultimodalAPI Available
Context Window1M tokens
VariantsGPT-5.5 Instant, GPT-5.5 Thinking, GPT-5.5 Pro
Description
OpenAI's current flagship model with a 1 million token context window. Available in Instant (speed-optimized), Thinking (deep reasoning), and Pro (maximum capability) variants. Represents OpenAI's most capable model for complex tasks, creative work, and multi-step agentic workflows.
Key Innovations
Reasoning
ReasoningStructured step-by-step problem solving, often using chain-of-thought or tree-of-thought approaches.
Multimodal
MultimodalProcessing multiple types of input (text, images, audio, video) in a single model.
Agentic
AgenticModels that can autonomously plan, execute multi-step tasks, use tools, and self-correct without human intervention.
Long Context
Long ContextAbility to process very long inputs (100K+ tokens), enabling analysis of entire codebases or books.