Grok 4.5 vs gpt-5-mini

xAI Grok 4.5OpenAI gpt-5-mini
VendorxAIOpenAI
Context window500,000400,000
Max output2,000,000128,000
ReasoningYesYes
Tool callingYesYes
File inputYesYes
Inputtext, imagetext, image
Outputtexttext
Released2026-07-082025-08-07