The closest alternative to GPT-5.1-Codex-Max is GPT Chat Latest — comparable intelligence (— vs —); for a cheaper option, MiniMax M3 runs $0.300/M vs $1.25/M; for more speed, Morph V3 Large hits 2.6k t/s; and the best open-weight substitute is MiniMax M3.
GPT Chat Latest is the closest alternative to GPT-5.1-Codex-Max, with an Intelligence Index of — (GPT-5.1-Codex-Max scores —) at $5.00 per million input tokens.
Yes — MiniMax M3 costs $0.300 per million input tokens versus $1.25 for GPT-5.1-Codex-Max, while staying within ~8 points of its Intelligence Index.
MiniMax M3 is the strongest open-weight alternative to GPT-5.1-Codex-Max — downloadable from Hugging Face and self-hostable, scoring 54.7 on intelligence.