OpenAI compatible API · Attested · Public status

DeepSeek: DeepSeek V4 Flash 0731 vs Step 3.5 Flash 2603

DeepSeek V4 Flash 0731 vs Step 3.5 Flash 2603: 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

$0.422/1MStep 3.5 Flash 2603 cheapest route

1089 msDeepSeek: DeepSeek V4 Flash 0731 fastest measured p50 TTFT via akashml

1490 msStep 3.5 Flash 2603 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 0731Step 3.5 Flash 2603

Model iddeepseek/deepseek-v4-flash-0731stepfun/step-3.5-flash-2603

Publisher DeepSeek StepFun

AI IQ — —

Context1,310,720 tokens262,144 tokens

Provider routes341

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

Privacy posturehas ZDR routeprovider posture varies

Fastest measured p50 TTFT1089 ms via akashml1490 ms via stepfun

Highest measured throughput58 tok/s via nextbitnot enough data

Recent route uptime range88.31% to 100.00%100.00%

Modes chat chat

DeepSeek: DeepSeek V4 Flash 0731 routes

Overview34 endpoints
PricingPrompt and completion rates
ProvidersAll serving providers

Step 3.5 Flash 2603 routes

Overview1 endpoints

Related comparisons

Browse every comparison

DeepSeek: DeepSeek V4 Flash 0731 vs Z.ai: GLM 5.286 combined provider routes
DeepSeek: DeepSeek V4 Flash 0731 vs MoonshotAI: Kimi K371 combined provider routes
DeepSeek: DeepSeek V4 Flash 0731 vs MoonshotAI: Kimi K2.665 combined provider routes
DeepSeek: DeepSeek V4 Flash 0731 vs OpenAI: gpt-oss-120b65 combined provider routes
DeepSeek: DeepSeek V4 Flash 0423 vs DeepSeek: DeepSeek V4 Flash 073163 combined provider routes
DeepSeek: DeepSeek V4 Flash 0731 vs DeepSeek: DeepSeek V4 Pro 042362 combined provider routes
DeepSeek: DeepSeek V4 Flash 0731 vs Google: Gemma 4 31B61 combined provider routes
DeepSeek: DeepSeek V4 Flash 0731 vs Z.ai: GLM 5.157 combined provider routes

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 Step 3.5 Flash 2603?

Is DeepSeek: DeepSeek V4 Flash 0731 or Step 3.5 Flash 2603 cheaper?

The current cheapest TrustedRouter route is $0.2743/1M for DeepSeek: DeepSeek V4 Flash 0731 and $0.422/1M for Step 3.5 Flash 2603. The comparison uses current catalog prices and updates as provider pricing changes.

Is DeepSeek: DeepSeek V4 Flash 0731 or Step 3.5 Flash 2603 faster?

Current measured p50 time to first token is 1089 ms for DeepSeek: DeepSeek V4 Flash 0731 and 1490 ms for Step 3.5 Flash 2603. These are routed probe measurements, not vendor-advertised speeds, and update as new samples arrive.

Can I test DeepSeek: DeepSeek V4 Flash 0731 and Step 3.5 Flash 2603 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-2603. This makes side-by-side evals possible without maintaining two provider integrations.