Comprehensive side-by-side LLM comparison
GPT-5 Mini supports multimodal inputs. Both models have their strengths depending on your specific coding needs.
OpenAI
GPT-5 mini, released by OpenAI in August 2025, is a smaller variant from the GPT-5 family that inherits GPT-5's unified reasoning architecture and multimodal capabilities at a reduced inference cost. It targets high-volume production use cases requiring a balance of intelligence and response speed, offering GPT-5 capabilities for applications where full GPT-5 inference costs are a concern.
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-5 Mini
OpenAI
2025-08
Step-3.5-Flash
StepFun
2026-02-02
Context window and performance specifications
Available providers and their performance metrics
GPT-5 Mini
OpenAI
Step-3.5-Flash
GPT-5 Mini
Step-3.5-Flash
GPT-5 Mini
Step-3.5-Flash