OpenAI compatible API · Attested · Public status

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

gpt-oss-120b 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

OpenAI: gpt-oss-120b has the lower cheapest prompt+completion route on TrustedRouter. OpenAI: gpt-oss-120b has more provider fallback routes, while Z.ai: GLM 5.3 Flash has the larger context window. Current TrustedRouter probes show OpenAI: gpt-oss-120b with the lower p50 TTFT.

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

$0.342875/1MZ.ai: GLM 5.3 Flash cheapest route

633 msOpenAI: gpt-oss-120b fastest measured p50 TTFT via fireworks

6157 msZ.ai: GLM 5.3 Flash fastest measured p50 TTFT via zai

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 105#67 IQ 121#20

Context131,072 tokens1,310,720 tokens

Provider routes3626

Cheapest route$0.211/1M$0.342875/1M

Privacy posturehas provider E2EE routehas ZDR route

Fastest measured p50 TTFT633 ms via fireworks6157 ms via zai

Highest measured throughputnot enough datanot enough data

Recent route uptime range100.00%100.00%

Modes chat chat

OpenAI: gpt-oss-120b routes

Overview36 endpoints
PricingPrompt and completion rates
ProvidersAll serving providers

Z.ai: GLM 5.3 Flash routes

Overview26 endpoints
PricingPrompt and completion 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?

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 $0.342875/1M 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 633 ms for OpenAI: gpt-oss-120b and 6157 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.