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o3 vs Step-3.5-Flash
Comprehensive side-by-side LLM comparison
o3 supports multimodal inputs. Both models have their strengths depending on your specific coding needs.
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OpenAI
OpenAI o3, released by OpenAI in April 2025, is a large reasoning model that applies extended chain-of-thought processing to deliver improved performance on complex math, science, and coding tasks. It features a 200K token context window and native image understanding, with demonstrated strong results on mathematics and software engineering benchmarks. o3 targets demanding analytical and engineering tasks where deliberate, multi-step reasoning produces significantly better outcomes than direct generation.
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StepFun
Step-3.5-Flash, released by StepFun on February 2, 2026, is a Mixture-of-Experts large language model with 197 billion total parameters and approximately 11 billion active parameters per inference. It features a 256K token context window using a 3:1 sliding-window-to-full-attention ratio, processing 100–350 tokens per second. Step-3.5-Flash targets agentic tasks, coding workflows, and open-source deployments requiring frontier reasoning capabilities with efficient inference, under an Apache 2.0 license.
9 months newer
o3
OpenAI
2025-04-16
Step-3.5-Flash
StepFun
2026-02-02
Performance Metrics
Context window and performance specifications
Provider Availability & Performance
Available providers and their performance metrics
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o3
1 providers
OpenAI
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Step-3.5-Flash
0 providers
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o3
Avg Score:0.0%
Providers:1
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Step-3.5-Flash
Avg Score:0.0%
Providers:0