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GPT-5.1 Codex Max vs Step-3.5-Flash
Comprehensive side-by-side LLM comparison
. Both models have their strengths depending on your specific coding needs.
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OpenAI
GPT-5.1 Codex Max, released by OpenAI in November 2025, is an enhanced coding variant from the GPT-5.1 Codex line, designed for more complex software engineering tasks requiring additional reasoning depth. It targets large-scale code generation, automated refactoring, and sophisticated agentic development workflows.
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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.
3 months newer
GPT-5.1 Codex Max
OpenAI
2025-11
Step-3.5-Flash
StepFun
2026-02-02
Provider Availability & Performance
Available providers and their performance metrics
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GPT-5.1 Codex Max
0 providers
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Step-3.5-Flash
0 providers
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GPT-5.1 Codex Max
Avg Score:0.0%
Providers:0
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Step-3.5-Flash
Avg Score:0.0%
Providers:0