The closest alternative to Mistral Small 4 is Hermes 4 405B — comparable intelligence (18.6 vs 18.6); for a cheaper option, MiMo-V2.5 runs $0.140/M vs $0.150/M; for more speed, Mercury 2 hits 590 t/s; and the best open-weight substitute is MiniMax M3.
Hermes 4 405B is the closest alternative to Mistral Small 4, with an Intelligence Index of 18.6 (Mistral Small 4 scores 18.6) at $1.00 per million input tokens.
Yes — MiMo-V2.5 costs $0.140 per million input tokens versus $0.150 for Mistral Small 4, while staying within ~8 points of its Intelligence Index.
MiniMax M3 is the strongest open-weight alternative to Mistral Small 4 — downloadable from Hugging Face and self-hostable, scoring 54.7 on intelligence.