OpenAI compatible API · Attested · Public status

Step 3.5 Flash 2603 vs Z.ai: GLM 5.3 Flash

Step 3.5 Flash 2603 vs Z.ai: GLM 5.3 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

Z.ai: GLM 5.3 Flash has the lower published input-plus-output rate, more Credits provider routes, the larger context window and the lower measured p50 time to first token.

$0.422/1MStep 3.5 Flash 2603 cheapest route

$0.32705/1MZ.ai: GLM 5.3 Flash cheapest route

2720 msStep 3.5 Flash 2603 fastest measured p50 TTFT via stepfun

771 msZ.ai: GLM 5.3 Flash fastest measured p50 TTFT via together

The price comparison adds each route's rate for one million input tokens and one million output tokens; your cost depends on your input/output mix. 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.

Step 3.5 Flash 2603Z.ai: GLM 5.3 Flash

Model idstepfun/step-3.5-flash-2603z-ai/glm-5.3-flash

Publisher StepFun Z.AI

AI IQ — IQ 120#38

Context262,144 tokens1,048,576 tokens

Credits provider routes125

Cheapest route$0.422/1M$0.32705/1M

Cached input$0.0211/1M$0.015825/1M to $0.110775/1M

Privacy postureprovider posture varieshas provider E2EE route

Fastest measured p50 TTFT2720 ms via stepfun771 ms via together

Highest measured throughputnot enough datanot enough data

Recent route uptime range100.00%0.00% to 100.00%

Modes chat chat

Step 3.5 Flash 2603 routes

Overview1 Credits routes

Z.ai: GLM 5.3 Flash routes

Overview25 Credits routes
PricingInput, cached input, and output rates
ProvidersAll serving providers

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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="stepfun/step-3.5-flash-2603",
    messages=messages,
)

Questions

Which should I use, Step 3.5 Flash 2603 or Z.ai: GLM 5.3 Flash?

Z.ai: GLM 5.3 Flash has the lower published input-plus-output rate, more Credits provider routes, the larger context window and the lower measured p50 time to first token.

Is Step 3.5 Flash 2603 or Z.ai: GLM 5.3 Flash cheaper?

The current cheapest TrustedRouter route is $0.422/1M for Step 3.5 Flash 2603 and $0.32705/1M for Z.ai: GLM 5.3 Flash. The comparison uses current catalog prices and updates as provider pricing changes.

Is Step 3.5 Flash 2603 or Z.ai: GLM 5.3 Flash faster?

Current measured p50 time to first token is 2720 ms for Step 3.5 Flash 2603 and 771 ms for Z.ai: GLM 5.3 Flash. These are routed probe measurements, not vendor-advertised speeds, and update as new samples arrive.

Can I test Step 3.5 Flash 2603 and Z.ai: GLM 5.3 Flash with the same API?

Yes. Use the same OpenAI-compatible TrustedRouter base URL and API key, then change only the model id between stepfun/step-3.5-flash-2603 and z-ai/glm-5.3-flash. This makes side-by-side evals possible without maintaining two provider integrations.