Step 3.5 Flash 2603 is optimized for high-frequency agentic and coding workflows with improved token efficiency and faster reasoning. NOTE: This model runs via StepFun, which may log and train on your prompts.
Added Apr 14, 2026
Context Window
256.0K
Max Output
256.0K
Avg output tokens (7d)
3.2K tokens
Input Price (Auto)
$0.10/1M
Output Price (Auto)
$0.30/1M
Cache Read (Auto)
$0.050/1M
Capabilities
Benchmarks
Benchmarks
Performance metrics and benchmarks
Sourced from Artificial Analysis.
Agentic work
T²-Bench Telecom (legacy)
Legacy fallback · Conversational AI agents in dual-control scenarios
87.4%
Better than 81% of models compared
Document reasoning
AA-LCR (unversioned / legacy)
Legacy fallback · Long context reasoning evaluation
63.0%
Better than 57% of models compared
Reasoning
HLE
Humanity's Last Exam
24.5%
Better than 76% of models compared
IFBench
Instruction-following benchmark
66.5%
Better than 79% of models compared
CritPt
Research-level physics reasoning
2.3%
Coding
Terminal-Bench Hard (legacy)
Legacy fallback · Agentic coding and terminal use
32.6%
Better than 77% of models compared
Knowledge
AA-Omniscience Accuracy
Proportion of correctly answered questions
24.6%
AA-Omniscience Hallucination Rate
Rate of incorrect answers among non-correct responses
91.3%
Legacy benchmarks
GPQA Diamond (legacy)
Graduate-level scientific reasoning
82.6%
Better than 71% of models compared
Last updated Sep 5, 2026, 12:00 AM
Artificial AnalysisProviders
Auto routing is available for this model. Explicit provider selection is not available.
Loading provider options…
Related text models
Compare Step 3.5 Flash 2603 with similar models from the same provider or model family.
Step 3.5 Flash
stepfun-ai/step-3.5-flashStepFun's most capable open-source reasoning model with visible reasoning traces. Built on a sparse Mixture-of-Experts architecture with 196B total parameters and only 11B active per token, it achieves frontier-level performance in math, logic, and agentic coding while reaching up to 350 tokens/sec. Supports 256K context. NOTE: This model runs via StepFun, which may log and train on your prompts.
Step 3.7 Flash Thinking
stepfun/step-3.7-flash:thinkingStep 3.7 Flash Thinking is StepFun's high-efficiency multimodal MoE model with visible reasoning enabled for deeper agentic coding, long-context reasoning, tool use, and native image/video understanding. ⚠️ Note: This model routes through StepFun, so privacy and logging guarantees may be limited.
DeepSeek V4.1 Flash
deepseek/deepseek-v4.1-flashDeepSeek V4.1 Flash supports text and image input, reasoning, tool calling, and structured output with a 1M-token context window. This is a rate-limited beta with limited capacity, intended for testing rather than production use. Assume prompts and responses are logged by the provider and may be used for model training or service improvement. Do not send sensitive or confidential data.
DeepSeek V4 Flash Vision Exp Uncensored
deepseek/deepseek-v4-flash-vision-exp-uncensoredAn uncensored variant of the experimental vision-enabled DeepSeek V4 Flash model for chat, image understanding, reasoning, coding, and tool use, with a 524K context window.
Synth 2.5 Flash Preview
synth-2.5-flashSynth 2.5 Flash Preview is a low-cost text model designed for role-play, character dialogue, and collaborative storytelling.
Gemini 3.8 Flash
google/gemini-3.8-flashGoogle's fast multimodal model for agentic workloads, including coding, tool use, image understanding, PDF and document extraction, audio, and video. Its capabilities, limits, reasoning behavior, and pricing currently mirror Gemini 3.7 Flash.