OpenAI compatible API · Attested · Public status

OpenAI: gpt-oss-120b vs Z.ai: GLM 5.3 Flash

gpt-oss-120b has the lower published input-plus-output rate and the lower measured p50 time to first token. Z.ai: GLM 5.3 Flash has more Credits provider routes and the larger context window. Compare price, speed, context, and privacy.

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

gpt-oss-120b has the lower published input-plus-output rate and the lower measured p50 time to first token. Z.ai: GLM 5.3 Flash has more Credits provider routes and the larger context window.

$0.211/1MOpenAI: gpt-oss-120b cheapest route

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

934 msOpenAI: gpt-oss-120b fastest measured p50 TTFT via akashml

1036 msZ.ai: GLM 5.3 Flash fastest measured p50 TTFT via fireworks

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.

OpenAI: gpt-oss-120bZ.ai: GLM 5.3 Flash

Model idopenai/gpt-oss-120bz-ai/glm-5.3-flash

Publisher OpenAI Z.AI

AI IQ IQ 98#126 IQ 120#42

Context131,072 tokens1,048,576 tokens

Credits provider routes2334

Cheapest route$0.211/1M$0.32705/1M

Cached input$0.015825/1M to $0.1055/1M$0.01266/1M to $0.076488/1M

Privacy posturehas Confidential route (E2EE + ZDR)has Confidential route (E2EE + ZDR)

Fastest measured p50 TTFT934 ms via akashml1036 ms via fireworks

Highest measured throughputnot enough datanot enough data

Recent route uptime range0.00% to 100.00%0.00% to 100.00%

Modes chat chat

OpenAI: gpt-oss-120b routes

Overview23 Credits routes
PricingInput, cached input, and output rates
ProvidersAll serving providers

Z.ai: GLM 5.3 Flash routes

Overview34 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="openai/gpt-oss-120b",
    messages=messages,
)

Questions

Which should I use, OpenAI: gpt-oss-120b or Z.ai: GLM 5.3 Flash?

gpt-oss-120b has the lower published input-plus-output rate and the lower measured p50 time to first token. Z.ai: GLM 5.3 Flash has more Credits provider routes and the larger context window.

Is OpenAI: gpt-oss-120b or Z.ai: GLM 5.3 Flash cheaper?

The current cheapest TrustedRouter route is $0.211/1M for OpenAI: gpt-oss-120b and $0.32705/1M for Z.ai: GLM 5.3 Flash. The comparison uses current catalog prices and updates as provider pricing changes.

Is OpenAI: gpt-oss-120b or Z.ai: GLM 5.3 Flash faster?

Current measured p50 time to first token is 934 ms for OpenAI: gpt-oss-120b and 1036 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 OpenAI: gpt-oss-120b 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 openai/gpt-oss-120b and z-ai/glm-5.3-flash. This makes side-by-side evals possible without maintaining two provider integrations.