Overview
GPT-5.5 is OpenAI’s flagship large language model designed for advanced coding, professional reasoning, long-context workflows, and autonomous AI agents. It delivers stronger reasoning, improved instruction following, better tool usage, and enhanced multimodal capabilities compared to previous GPT-5 series models.
The model supports a massive 1M+ token context window, enabling complex long-running tasks such as software engineering, document analysis, research workflows, enterprise automation, and AI agent systems. GPT-5.5 also introduces configurable reasoning effort levels for balancing intelligence and latency in production environments.
- Advanced coding and software engineering capabilities
- 1M+ token long-context processing
- Improved reasoning and instruction following
- Supports tool calling and autonomous agents
- Optimized for enterprise and developer workflows
- Available via OpenAI API, ChatGPT, and Codex
Model Specifications
- Feature — Details
- Context Window — 1,050,000 tokens
- Max Output — 128,000 tokens
- Modalities — Text + Image Input
- Reasoning Levels — none, low, medium, high, xhigh
- Knowledge Cutoff — December 2025
