GPT-5.1-Codex alternatives
Match · Updated July 2026
The closest alternative to GPT-5.1-Codex is Claude Opus 4.5 — comparable intelligence (34.7 vs 34.7); for a cheaper option, GPT-5.6 Terra runs $1.00/M vs $1.25/M; and the best open-weight substitute is Kimi K3.
Closest match
Cheaper alternatives
gpt-5.6-terra
$1.00/M input · 55.0 intel
claude-sonnet-5:batch
$1.00/M input · 53.4 intel
gpt-5.6-luna
$0.100/M input · 51.2 intel
glm-5.2
$0.966/M input · 51.1 intel
gemini-3.5-flash:batch
$0.750/M input · 50.2 intel
gemini-3.6-flash:batch
$0.750/M input · 50.1 intel
Smarter alternatives
kimi-k2.5
35.4 intel · $0.570/M
claude-sonnet-4.6
35.9 intel · $3.00/M
gemini-3.5-flash-lite
36.5 intel · $0.300/M
gemini-3.5-flash-lite:batch
36.5 intel · $0.150/M
gpt-5.1
36.9 intel · $1.25/M
gpt-5.1:batch
36.9 intel · $0.625/M
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 GPT-5.1-Codex?
Claude Opus 4.5 is the closest alternative to GPT-5.1-Codex, with an Intelligence Index of 34.7 (GPT-5.1-Codex scores 34.7) at $5.00 per million input tokens.
Is there a cheaper alternative to GPT-5.1-Codex?
Yes — GPT-5.6 Terra costs $1.00 per million input tokens versus $1.25 for GPT-5.1-Codex, while staying within ~8 points of its Intelligence Index.
Is there an open-source alternative to GPT-5.1-Codex?
Kimi K3 is the strongest open-weight alternative to GPT-5.1-Codex — downloadable from Hugging Face and self-hostable, scoring 57.1 on intelligence.