o3 alternatives
Match · Updated July 2026
The closest alternative to o3 is Step 3.7 Flash — comparable intelligence (30.3 vs 30.4); for a cheaper option, GPT-5.6 Terra runs $1.00/M vs $2.00/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-5.4:batch
$1.25/M input · 51.4 intel
gpt-5.6-luna
$0.100/M input · 51.2 intel
glm-5.2
$0.966/M input · 51.1 intel
muse-spark-1.1
$1.25/M input · 50.6 intel
Smarter alternatives
IReasoningTools+1ReasoningTools+2
ReasoningTools+1
ReasoningTools+2ReasoningTools+1ReasoningTools+2
ring-2.6-1t
30.6 intel · $0.075/M
gpt-5.1-codex-mini
30.6 intel · $0.250/M
minimax-m2.1
31.4 intel · $0.300/M
qwen3.6-35b-a3b
31.6 intel · $0.140/M
qwen3-max-thinking
31.7 intel · $0.780/M
qwen3.5-122b-a10b
32.3 intel · $0.260/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 o3?
Step 3.7 Flash is the closest alternative to o3, with an Intelligence Index of 30.3 (o3 scores 30.4) at $0.200 per million input tokens.
Is there a cheaper alternative to o3?
Yes — GPT-5.6 Terra costs $1.00 per million input tokens versus $2.00 for o3, while staying within ~8 points of its Intelligence Index.
Is there an open-source alternative to o3?
Kimi K3 is the strongest open-weight alternative to o3 — downloadable from Hugging Face and self-hostable, scoring 57.1 on intelligence.