Fallback Chains

Set model to a > separated list of model IDs. If the first model fails or scores below your quality threshold, the next one runs automatically.

Request

{
  "model": "claude-opus-4.6>gpt-5>gemini-3.1-pro",
  "messages": [{"role": "user", "content": "Review this contract clause..."}],
  "min_quality": 0.85
}

Response

{
  "model": "gpt-5",
  "fallback": {
    "chain": ["claude-opus-4.6", "gpt-5", "gemini-3.1-pro"],
    "triggered": true,
    "attempts": [
      {"model": "claude-opus-4.6", "success": false, "error": "timeout"},
      {"model": "gpt-5", "success": true, "quality_score": 0.94}
    ]
  },
  "cost": {"this_request": "$0.006"}
}

Parameters

Parameter	Type	Default	Description
`model`	string	—	Up to 4 models separated by `>`. Example: `"a>b>c"`
`min_quality`	number	—	If the response scores below this (0–1), fall back to the next model.
`fallback_on_error`	boolean	`true`	Continue to the next model on error. Set to `false` to fail immediately.

Billing

You’re charged for each model that runs successfully. If the first model times out and the second succeeds, you pay only for the second.

Code examples

import requests, os

r = requests.post("https://www.ninjachat.ai/api/v1/chat",
    headers={"Authorization": f"Bearer {os.environ['NINJACHAT_API_KEY']}"},
    json={
        "model": "claude-opus-4.6>gpt-5>gemini-3.1-pro",
        "messages": [{"role": "user", "content": "Analyze this legal document..."}],
        "min_quality": 0.85,
    }
)
data = r.json()
print(f"Resolved to: {data['model']}")
print(f"Fallback triggered: {data['fallback']['triggered']}")

curl -X POST https://www.ninjachat.ai/api/v1/chat \
  -H "Authorization: Bearer nj_sk_YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-4.6>gpt-5>gemini-3.1-pro",
    "messages": [{"role": "user", "content": "Summarize this research paper..."}],
    "min_quality": 0.8
  }'

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Reference

Request

Response

Parameters

Billing

Code examples

​Request

​Response

​Parameters

​Billing

​Code examples

Request

Response

Parameters

Billing

Code examples