Comprehensive side-by-side LLM comparison
. Both models have their strengths depending on your specific coding needs.
OpenAI
GPT-OSS-20B is an open-weight large language model with 20 billion parameters from OpenAI's open-source model initiative. It targets deployments requiring a smaller, efficient model that can run on consumer or mid-tier hardware while maintaining strong reasoning and coding capabilities relative to its size.
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.
6 months newer

GPT-OSS-20B
OpenAI
2025-08-05
Step-3.5-Flash
StepFun
2026-02-02
Context window and performance specifications
Available providers and their performance metrics
GPT-OSS-20B
Hugging Face
Step-3.5-Flash
GPT-OSS-20B
Step-3.5-Flash
GPT-OSS-20B
Step-3.5-Flash