OpenAI API — April, 2026

April 1, 2026

This release introduces new GPT-5.5 models, including a Pro version, for complex professional work, featuring a 1M token context, image input, tool use, and web search. Also new is GPT Image 2, a state-of-the-art model for image generation and editing with flexible sizing and discounted Batch API support. Key updates include a default medium reasoning effort for GPT-5.5, specific image_detail behavior, and a requirement for extended prompt caching. Significant enhancements to the Agents SDK provide controlled sandbox execution, customizable open-source harnesses, and refined memory management.

Added

Released GPT-5.5, a new frontier model for complex professional work, to the Chat Completions and Responses API, and released GPT-5.5 Pro for Responses API requests for tougher problems that benefit from more compute.
Released GPT Image 2, a state-of-the-art image generation model for image generation and editing. GPT Image 2 supports flexible image sizes, high-fidelity image inputs, token-based image pricing, and Batch API support with a 50% discount.
Updated the Agents SDK with new capabilities, including:

Changed

GPT-5.5 supports a 1M token context window, image input, structured outputs, function calling, prompt caching, Batch, tool search, built-in computer use, hosted shell, apply patch, Skills, MCP, and web search. Key updates include:
Reasoning effort now defaults to medium.
When image_detail is unset or set to auto, the model now uses original behavior.
Caching for GPT-5.5 only works with extended prompt caching. In-memory prompt caching is not supported. Learn more here.
running agents in controlled sandboxes;
inspecting and customizing the open-source harness; and
controlling when memories are created and where they're stored.