AI Models · Open-Source vs Paid

Step 3.7 Flash Open vs GPT-3.5 Turbo (older v0613) Paid

Step 3.7 Flash vs GPT-3.5 Turbo (older v0613) compared — price per token, context window, multimodality, openness and which to choose. Can the open-source model replace the paid one? Full 2026 breakdown.

Prices & specs refreshed from live data · olud.ai

Open-model prices = cheapest provider via OpenRouter; official maker rates may be higher.

Step 3.7 FlashOpenStepfun
$0.2 /M input
$1.15 /M outputNo per-token fees if you self-host
TypeOpen-weight
Context window262K tokens
MultimodalYes
Self-hostYes
GPT-3.5 Turbo (older v0613)PaidOpenAI
$1 /M input
$2 /M outputManaged API (no infra to run)
TypeProprietary
Context window4K tokens
MultimodalNo
Self-hostNo
Choose Step 3.7 Flash if you want to self-host, keep your data private and skip per-token fees — it's open-weight and runs on your own hardware. Choose GPT-3.5 Turbo (older v0613) if you want frontier capability through a managed API with zero infrastructure to run.

Step 3.7 Flash vs GPT-3.5 Turbo (older v0613) specs

SpecStep 3.7 FlashGPT-3.5 Turbo (older v0613)Winner
MakerStepfunOpenAI
TypeOpen-weightProprietaryStep 3.7 Flash
Context window262K tokens4K tokensStep 3.7 Flash
Input price$0.2/M · free self-host$1/MStep 3.7 Flash
Output price$1.15/M · free self-host$2/MStep 3.7 Flash
Vision / multimodalYesNoStep 3.7 Flash
Tool / function callingYesYes= Tie
Self-hostableYesNo (API only)Step 3.7 Flash
LicenseOpen weightsProprietaryStep 3.7 Flash

Price gap & when to choose each

1.7×cheaper per output token

Step 3.7 Flash is ~1.7× cheaper than GPT-3.5 Turbo (older v0613) on output tokens ($1.15 vs $2 per M tokens).

Choose Step 3.7 Flash if…
  • You want to self-host or run on your cloud
  • You need the longer 262K context window
  • You prioritize data privacy & control
  • You want the lowest operating costs
  • You are building open or reproducible AI
Choose GPT-3.5 Turbo (older v0613) if…
  • You want frontier performance through a managed API
  • You value reliability & ecosystem
  • You don't want to manage infrastructure

Feature comparison

CapabilityStep 3.7 FlashGPT-3.5 Turbo (older v0613)
Open weights (downloadable)
Self-hostable
Runs fully offline
Vision / multimodal
Tool / function calling
1M+ context window

Benchmarks: Step 3.7 Flash vs GPT-3.5 Turbo (older v0613)

Independent benchmark scores measured by Artificial Analysis. Higher is better (except latency).

Step 3.7 Flash delivers 6.1× more intelligence per dollar.
Step 3.7 Flash
GPT-3.5 Turbo (older v0613)
Intelligence index
19.5
5.5
Coding index
39.6
10.7
GPQA
80.9%
29.7%
Humanity's Last Exam
21.4%
Long Context Reasoning
73.7%
SciCode
43.9%
IFBench
67.3%
τ²-Bench
98.5%
τ-Bench Banking
12%
Terminal-Bench
39.3%
Terminal-Bench Hard
35.6%
MMLU-Pro
46.2%
MATH-500
44.1%
Speed
132.8 tok/s
0 tok/s
Latency
1.59s
0s
Intelligence per $
44.5
7.3

Benchmark data by Artificial Analysis.

How Step 3.7 Flash and GPT-3.5 Turbo (older v0613) score

🏆 Best value & openness: Step 3.7 Flash (4.7 vs 2.5 / 5)
CriterionStep 3.7 FlashGPT-3.5 Turbo (older v0613)
Cost-efficiency4.54.5
Context window4.02.0
Openness5.01.5
Self-hosting5.01.0
Multimodality5.03.5

Scores come from live data — output price (cost), context length, open vs closed weights (openness & self-hosting) and vision/tool support (multimodality). Raw task quality isn't scored here; it depends on your benchmark — see the verdict.

What each model is

Step 3.7 Flash Open

Stepfun · Open-weight

Step 3.7 Flash is StepFun's latest high-efficiency multimodal Mixture-of-Experts model. It pairs a 196B-parameter language backbone with a vision encoder for native image and video understanding, activating roughly 11B parameters...

GPT-3.5 Turbo (older v0613) Paid

OpenAI · Proprietary

GPT-3.5 Turbo is OpenAI's fastest model. It can understand and generate natural language or code, and is optimized for chat and traditional completion tasks. Training data up to Sep 2021.

Other models in these families

These variants are tracked but not compared here — one page per family keeps the comparison readable.

Other variants tracked
Step 3.5 Flash

Frequently asked questions

Is Step 3.7 Flash as good as GPT-3.5 Turbo (older v0613)?

Step 3.7 Flash is open-weight and competitive on many tasks, but GPT-3.5 Turbo (older v0613) may still lead on the hardest reasoning and agentic work. The gap keeps narrowing — benchmark both on your actual use case before deciding.

Can I run Step 3.7 Flash locally?

Yes. Step 3.7 Flash has open weights, so you can self-host it on your own GPUs or run it via a low-cost API. GPT-3.5 Turbo (older v0613) is API-only and cannot be self-hosted.

How much cheaper is Step 3.7 Flash?

Step 3.7 Flash costs $1.15/M output vs $2/M for GPT-3.5 Turbo (older v0613) — roughly 2x cheaper via API, and free if you self-host.

Step 3.7 Flash vs GPT-3.5 Turbo (older v0613) — which should I pick in 2026?

Choose Step 3.7 Flash if you want to self-host, keep your data private and skip per-token fees — it's open-weight and runs on your own hardware. Choose GPT-3.5 Turbo (older v0613) if you want frontier capability through a managed API with zero infrastructure to run.

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