The closest alternative to Claude Opus 4.1 is Claude Fable 5 — comparable intelligence (64.9 vs —); for a cheaper option, Claude Fable 5 runs $10.00/M vs $15.00/M; for more speed, Morph V3 Large hits 2.6k t/s; and the best open-weight substitute is MiniMax M3.
Claude Fable 5 is the closest alternative to Claude Opus 4.1, with an Intelligence Index of 64.9 (Claude Opus 4.1 scores —) at $10.00 per million input tokens.
Yes — Claude Fable 5 costs $10.00 per million input tokens versus $15.00 for Claude Opus 4.1, while staying within ~8 points of its Intelligence Index.
MiniMax M3 is the strongest open-weight alternative to Claude Opus 4.1 — downloadable from Hugging Face and self-hostable, scoring 54.7 on intelligence.