xAI Launches Grok 4.3 on API as Fastest Reasoning Model

Details

• xAI released Grok 4.3 on its API, describing it as the fastest and most intelligent model yet, optimized for complex reasoning tasks like advanced logic, math, scientific analysis, and multi-step investigations.
• Tops Artificial Analysis leaderboards in agentic tool calling and instruction following; ranks #1 on ValsAI in enterprise domains including case law and corporate finance.
• Features improved architecture over Grok 4.20, 1 million-token context window (roughly 2,000 pages of text), and knowledge cutoff of December 2025.
• Supports native video input (up to 5 minutes, 1080p), image inputs, function calling, web search, X search, code execution, and RAG; generates downloadable PDFs, PowerPoint decks, and Excel spreadsheets.
• API pricing at $1.25 per million input tokens positions it as xAI's cheapest frontier-tier model; available to all developers with consumer access via SuperGrok plans.

Impact

Grok 4.3 pressures rivals like OpenAI's GPT-5.5 and Anthropic's Claude Opus 4.7 by offering top benchmark scores in agentic workflows and instruction following at lower API costs, enabling high-volume use in research agents, customer support, coding, and document analysis. Its 1M-token context and native video/file capabilities widen access for developers building multimodal applications, while strong enterprise domain performance could accelerate adoption in finance and legal sectors. This cements xAI's niche in cost-efficient, reasoning-focused frontier models without displacing leaders in raw intelligence.