Spend controls

const response = await client.responses.create({
  model: "ninja/auto",
  input: "Translate to Spanish: Hello world",
  max_output_tokens: 80,
  routing: {
    strategy: "cost",
    max_cost_usd: 0.005,
    allow_fallbacks: true,
  },
});

console.log(response.cost_usd, response.routing.resolved_model);

response = client.responses.create(
    model="ninja/auto",
    input="Translate to Spanish: Hello world",
    max_output_tokens=80,
    routing={"strategy": "cost", "max_cost_usd": 0.005, "allow_fallbacks": True},
)

curl https://www.ninjachat.ai/api/v1/responses \
  -H "Authorization: Bearer $NINJACHAT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"ninja/auto","input":"Translate to Spanish: Hello world","routing":{"strategy":"cost","max_cost_usd":0.005}}'

​

Parameters

​

How the cap is enforced

1. Before any provider call, the gateway computes the maximum token hold for the request: your input estimate plus the output ceiling, priced at the candidate models’ metered rates. If that hold is above max_cost_usd, the request is rejected with 400 max_cost_exceeded and nothing runs:
   {
     "error": {
       "message": "The maximum token hold is $0.012000, above routing.max_cost_usd=$0.005000.",
       "type": "invalid_request_error",
       "code": "max_cost_exceeded",
       "param": "routing.max_cost_usd"
     },
     "maximum_hold_usd": 0.012
   }
   
   Lower max_output_tokens, pick cheaper candidates, or raise the cap.
2. At settle time, the metered charge is capped at max_cost_usd. Usage priced above the cap is absorbed by NinjaChat — it is logged, never billed to you.

​

Where it shines

BUDGETS = {"free": 0.005, "pro": 0.05, "enterprise": 0.50}  # USD per request

def chat_for(plan: str, message: str):
    return client.responses.create(
        model="ninja/auto",
        input=message,
        routing={"strategy": "cost", "max_cost_usd": BUDGETS[plan]},
    )