Private AI
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
Input Price (Auto)
$0.10/1M
Output Price (Auto)
$0.30/1M
Cache Read (Auto)
$0.050/1M
Capabilities
Performance metrics and benchmarks
Sourced from Artificial Analysis.
GPQA Diamond
Graduate-level scientific reasoning
82.6%
Better than 76% of models compared
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HLE
Humanity's Last Exam
22.6%
Better than 82% of models compared
IFBench
Instruction-following benchmark
66.5%
Better than 79% of models compared
T²-Bench Telecom
Conversational AI agents in dual-control scenarios
87.4%
Better than 81% of models compared
AA-LCR
Long context reasoning evaluation
54.3%
Better than 61% of models compared
CritPt
Research-level physics reasoning
2.3%
SciCode
Python programming for scientific computing
38.5%
Better than 66% of models compared
Terminal-Bench Hard
Agentic coding and terminal use
32.6%
Better than 77% of models compared
AA-Omniscience Accuracy
Proportion of correctly answered questions
25.0%
AA-Omniscience Hallucination Rate
Rate of incorrect answers among non-correct responses
91.6%
Last updated Jun 19, 2026, 12:00 PM
Artificial Analysis