Grok 4.3 vs GPT-5

xAI Grok 4.3OpenAI GPT-5
VendorxAIOpenAI
Context window2,000,000400,000
Max output2,000,000128,000
ReasoningYesYes
Tool callingYesYes
File inputYesYes
Inputtext, imagetext, image
Outputtexttext
Released2026-05-022025-08-07