OpenAI compatible API · Attested · Public status

DeepSeek: DeepSeek V4 Flash 0731 vs StepFun: Step 3.5 Flash

DeepSeek V4 Flash 0731 vs Step 3.5 Flash: compare current API pricing, context, provider routes, privacy, p50 latency, and OpenAI-compatible access.

Verify gateway

Onebase URL to migrate

100sof models and routes

0prompt or output logs. Always.

Compare routesProviders, price, context, and policy posture in one view.

Use auto when uptime mattersKeep a primary model and let fallback handle provider failures.

Same API shapeUse the OpenAI client and set the model you want.

Practical read

Monthly evidence

DeepSeek: DeepSeek V4 Flash 0731 has the lower cheapest prompt+completion route on TrustedRouter. DeepSeek: DeepSeek V4 Flash 0731 has more provider fallback routes, while DeepSeek: DeepSeek V4 Flash 0731 has the larger context window. Current TrustedRouter probes show DeepSeek: DeepSeek V4 Flash 0731 with the lower p50 TTFT.

$0.2743/1MDeepSeek: DeepSeek V4 Flash 0731 cheapest route

$0.422/1MStepFun: Step 3.5 Flash cheapest route

870 msDeepSeek: DeepSeek V4 Flash 0731 fastest measured p50 TTFT via inceptron

2800 msStepFun: Step 3.5 Flash fastest measured p50 TTFT via stepfun

Prices and live route measurements can change. Use the monthly reports when you need a stable evidence window, then run a small task-specific eval before choosing a production default.

DeepSeek: DeepSeek V4 Flash 0731StepFun: Step 3.5 Flash

Model iddeepseek/deepseek-v4-flash-0731stepfun/step-3.5-flash

Publisher DeepSeek StepFun

AI IQ — —

Context1,310,720 tokens262,144 tokens

Provider routes351

Cheapest route$0.2743/1M$0.422/1M

Privacy posturehas ZDR routeprovider posture varies

Fastest measured p50 TTFT870 ms via inceptron2800 ms via stepfun

Highest measured throughput173 tok/s via io-netnot enough data

Recent route uptime range60.00% to 100.00%100.00%

Modes chat chat

DeepSeek: DeepSeek V4 Flash 0731 routes

Overview35 endpoints
PricingPrompt and completion rates
ProvidersAll serving providers

StepFun: Step 3.5 Flash routes

Overview1 endpoints

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Production choice

Pick a default model. Keep fallback enabled.

TrustedRouter is useful when you know the model you want, but still need provider rollover, budget limits, usage records, and a prompt path you can verify.

OpenAI clientPython

client = OpenAI(
    base_url="https://api.trustedrouter.com/v1",
    api_key="sk-tr-v1-..."
)

response = client.chat.completions.create(
    model="deepseek/deepseek-v4-flash-0731",
    messages=messages,
)

Questions

Which should I use, DeepSeek: DeepSeek V4 Flash 0731 or StepFun: Step 3.5 Flash?

Is DeepSeek: DeepSeek V4 Flash 0731 or StepFun: Step 3.5 Flash cheaper?

The current cheapest TrustedRouter route is $0.2743/1M for DeepSeek: DeepSeek V4 Flash 0731 and $0.422/1M for StepFun: Step 3.5 Flash. The comparison uses current catalog prices and updates as provider pricing changes.

Is DeepSeek: DeepSeek V4 Flash 0731 or StepFun: Step 3.5 Flash faster?

Current measured p50 time to first token is 870 ms for DeepSeek: DeepSeek V4 Flash 0731 and 2800 ms for StepFun: Step 3.5 Flash. These are routed probe measurements, not vendor-advertised speeds, and update as new samples arrive.

Can I test DeepSeek: DeepSeek V4 Flash 0731 and StepFun: Step 3.5 Flash with the same API?

Yes. Use the same OpenAI-compatible TrustedRouter base URL and API key, then change only the model id between deepseek/deepseek-v4-flash-0731 and stepfun/step-3.5-flash. This makes side-by-side evals possible without maintaining two provider integrations.