OpenAI compatible API · Attested · Public status

MoonshotAI: Kimi K3 vs StepFun: Step 3.5 Flash

MoonshotAI: Kimi K3 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

StepFun: Step 3.5 Flash has the lower cheapest prompt+completion route on TrustedRouter. MoonshotAI: Kimi K3 has more provider fallback routes, while MoonshotAI: Kimi K3 has the larger context window. Current TrustedRouter probes show MoonshotAI: Kimi K3 with the lower p50 TTFT.

$12.66/1MMoonshotAI: Kimi K3 cheapest route

$0.422/1MStepFun: Step 3.5 Flash cheapest route

1128 msMoonshotAI: Kimi K3 fastest measured p50 TTFT via telnyx

1732 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.

MoonshotAI: Kimi K3StepFun: Step 3.5 Flash

Model idmoonshotai/kimi-k3stepfun/step-3.5-flash

Publisher Kimi StepFun

AI IQ IQ 123#17 —

Context1,048,576 tokens262,144 tokens

Provider routes371

Cheapest route$12.66/1M$0.422/1M

Privacy posturehas provider E2EE routeprovider posture varies

Fastest measured p50 TTFT1128 ms via telnyx1732 ms via stepfun

Highest measured throughput79 tok/s via basetennot enough data

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

Modes chat chat

MoonshotAI: Kimi K3 routes

Overview37 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="moonshotai/kimi-k3",
    messages=messages,
)

Questions

Which should I use, MoonshotAI: Kimi K3 or StepFun: Step 3.5 Flash?

Is MoonshotAI: Kimi K3 or StepFun: Step 3.5 Flash cheaper?

The current cheapest TrustedRouter route is $12.66/1M for MoonshotAI: Kimi K3 and $0.422/1M for StepFun: Step 3.5 Flash. The comparison uses current catalog prices and updates as provider pricing changes.

Is MoonshotAI: Kimi K3 or StepFun: Step 3.5 Flash faster?

Current measured p50 time to first token is 1128 ms for MoonshotAI: Kimi K3 and 1732 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 MoonshotAI: Kimi K3 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 moonshotai/kimi-k3 and stepfun/step-3.5-flash. This makes side-by-side evals possible without maintaining two provider integrations.