Step 3.5 Flash 2603
Step 3.5 Flash 2603 is a code model from Stepfun with Open Weights parameters, supporting a 256,000-token context window, with text modalities. Open-weight for self-hosted or compatible deployments.
Step 3.5 Flash 2603
Step 3.5 Flash 2603 is a code model from Stepfun with Open Weights parameters, supporting a 256,000-token context window, with text modalities. Open-weight for self-hosted or compatible deployments.
Hardware & Execution ParametersCode
Genealogical Graph & Evolutionary Provenance
Tracing foundational base architecture ancestry, architectural successors, scale siblings, and reasoning distillation derivatives.
Step 3.5 Flash 2603 operates as an autonomous foundation model architecture without direct precursor derivatives in this catalog.
Architecture Engineering & Capability Deep-Dive
An objective architectural evaluation of Step 3.5 Flash 2603 by Stepfun, analyzing underlying compute dynamics, memory constraints, and deployment economics.
Topology & Attention Mechanics
A robust autoregressive transformer utilizing standard attention patterns for predictable and coherent token generation.
Evaluation Profile & Reasoning
Exhibits frontier-tier behavior in reasoning and coding.
LLM Hardware Sizing & Serving
For open deployments via vLLM/SGLang, quantization (INT4/AWQ) is heavily recommended to fit dense memory constraints, or multi-GPU pipeline parallelism for full FP16.
Inference Economics & Workflows
Well-suited for enterprise pipelines where capability is balanced against per-million token costs.
Architectural Strengths vs. Considerations
An objective balance sheet analyzing the operational advantages and production constraints of deploying Step 3.5 Flash 2603.
Key Architectural Strengths
- Massive 256,000-token context allows full-repository and book-length ingestion.
- Demonstrated Artificial Analysis Coding Index evaluation score of 34.6% in verified benchmarks.
Operational Considerations
- 128k+ token prefill stages become heavily compute-bound and balloon KV cache without PagedAttention chunking.
Inference Runtimes & Hardware Sizing
Deployment targets, inference engines, and memory requirements for Step 3.5 Flash 2603.
python3 -m vllm.entrypoints.openai.api_server --model Step 3.5 Flash 2603 --tensor-parallel-size 1 --gpu-memory-utilization 0.95 --max-model-len 4096 --enable-chunked-prefillollama run step 3.5 flash 2603python3 -m sglang.launch_server --model-path Step 3.5 Flash 2603 --tp 1 --trust-remote-codetext-generation-launcher --model-id Step 3.5 Flash 2603 --num-shard 1 --max-batch-prefill-tokens 32000High-throughput PagedAttention server
One-click CLI & local desktop serving
Fast multi-turn structured decoding
Text Generation Inference
GGUF CPU/Apple Silicon execution
~0.0 GB VRAM required
~0.0 GB VRAM (Hopper speedup)
~0.0 GB VRAM
CPU RAM / Apple Silicon optimized
LLM Benchmark Database & Performance Metrics
3 TestedStandardized evaluation results across reasoning, agentic coding, computer use, and alignment.
API & Deployment Pricing
Open-weights model available for local and private cloud deployment. Compute costs depend on the target GPU hardware instance.
| Deployment Tier | Pricing Structure |
|---|---|
| Open Checkpoint Weights | $0.00 (Free Download) |
| Inference Token Consumption | $0.00 / Token |
Comparable Foundation Architectures
Alternative models in the Code class with similar capabilities, context windows, or deployment profiles.
DeepSeek V4 Flash Vision Exp
import os
from openai import OpenAI
client = OpenAI(
api_key=os.environ.get("STEPFUN_KEY", "EMPTY"),
base_url="http://localhost:8000/v1"
)
response = client.chat.completions.create(
model="stepfun-step-3.5-flash-2603",
messages=[{"role": "user", "content": "Explain quantum superposition in 2 sentences."}]
)
print(response.choices[0].message.content)Frequently Asked Questions about Step 3.5 Flash 2603
Essential facts, architectural specs, hardware constraints, and pricing answers for Step 3.5 Flash 2603.
To run Step 3.5 Flash 2603 (Open Weights) locally, you generally need Depends on quantization. We recommend using quantized GGUF/AWQ formats with Ollama or vLLM to optimize memory footprint.
All technical specifications, parameter distributions, context architectures, and benchmark evaluations for Step 3.5 Flash 2603 are audited against primary source release documentation, research whitepapers, and verified vendor API endpoints.