Claude Sonnet 4 alternatives
Match · Updated July 2026
The closest alternative to Claude Sonnet 4 is o4 Mini High — comparable intelligence (25.6 vs 25.5); for a cheaper option, Claude Opus 4.8 (batch) runs $2.50/M vs $3.00/M; and the best open-weight substitute is Kimi K3.
Closest match
Cheaper alternatives
claude-opus-4.8:batch
$2.50/M input · 55.7 intel
gpt-5.6-terra
$1.00/M input · 55.0 intel
gpt-5.5:batch
$2.50/M input · 54.8 intel
grok-4.5
$2.00/M input · 53.8 intel
claude-opus-4.7:batch
$2.50/M input · 53.5 intel
claude-sonnet-5
$2.00/M input · 53.4 intel
Smarter alternatives
Open-source alternatives
kimi-k3
57.1 intel · open weights · 1.0M ctx
glm-5.2
51.1 intel · open weights · 1.0M ctx
minimax-m3
44.4 intel · open weights · 1.0M ctx
minimax-m3:batch
44.4 intel · open weights · 524K ctx
deepseek-v4-pro
44.3 intel · open weights · 1.0M ctx
kimi-k2.6
44.2 intel · open weights · 262K ctx
Frequently asked
What is the best alternative to Claude Sonnet 4?
o4 Mini High is the closest alternative to Claude Sonnet 4, with an Intelligence Index of 25.6 (Claude Sonnet 4 scores 25.5) at $1.10 per million input tokens.
Is there a cheaper alternative to Claude Sonnet 4?
Yes — Claude Opus 4.8 (batch) costs $2.50 per million input tokens versus $3.00 for Claude Sonnet 4, while staying within ~8 points of its Intelligence Index.
Is there an open-source alternative to Claude Sonnet 4?
Kimi K3 is the strongest open-weight alternative to Claude Sonnet 4 — downloadable from Hugging Face and self-hostable, scoring 57.1 on intelligence.