DeepSeek V4, Grok 4.3, and GPT-5.5 reshape the model landscape.

DeepSeek released two variants of its V4 flagship on April 24, 2026. V4 Flash and V4 Pro both support 1 million token context windows, allowing entire codebases or long documents to be processed in a single prompt. The startup introduced a Hybrid Attention Architecture designed to improve long-context memory retention and reasoning performance.

Architecture and performance

xAI released Grok 4.3 on April 24, 2026, exiting experimental preview and immediately claiming the number two position on global model leaderboards. The architecture departs from monolithic design: instead of a single model, Grok 4.3 runs four distinct agents in parallel at inference time. The main Grok agent coordinates incoming queries; Harper pulls real-time data from X and performs fact-checking; Benjamin handles pure logic and coding tasks; Lucas focuses on creative reasoning. The agents debate each other in real-time before streaming a single finalized output.

Real-time data and pricing

OpenAI released GPT-5.5 on April 23, 2026, rolling the model to paid subscribers across all tiers (Plus, Pro, Business, and Enterprise) via ChatGPT and Codex. The release follows GPT-5.4 by less than two months, underscoring the accelerating pace of frontier model development. OpenAI President Greg Brockman highlighted that the model's defining characteristic is its ability to accomplish complex tasks with minimal guidance.

Autonomous reasoning focus