Documentation Index
Fetch the complete documentation index at: /llms.txt
Use this file to discover all available pages before exploring further.
Control the tradeoff between cost and latency using the service_tier parameter. ARouter passes service tier preferences to providers that support it.
service_tier parameter lets you express a preference for how ARouter and the upstream provider should balance cost and latency for a request.
{
"model": "openai/gpt-5.4",
"messages": [{"role": "user", "content": "Hello"}],
"service_tier": "auto"
}
| Value | Description |
|---|---|
"auto" (default) | Provider picks the appropriate tier based on availability |
"default" | Standard tier — best cost-performance balance |
"flex" | Reduced cost, best-effort latency — ideal for batch workloads |
| Provider | Supported values | Notes |
|---|---|---|
| OpenAI | "auto", "default", "flex" | "flex" offers reduced pricing for batch-like workloads |
| Others | Ignored | Passed through but has no effect |
service_tier used is echoed back in the response:
{
"id": "gen-...",
"model": "openai/gpt-5.4",
"service_tier": "default",
"choices": [...],
"usage": {...}
}
# Process large volumes at reduced cost
for document in documents:
response = client.chat.completions.create(
model="openai/gpt-5.4",
messages=[{"role": "user", "content": f"Summarize: {document}"}],
extra_body={"service_tier": "flex"},
)
# Real-time user-facing responses
response = client.chat.completions.create(
model="openai/gpt-5.4",
messages=[{"role": "user", "content": user_message}],
extra_body={"service_tier": "default"},
)