Retrying requests is a common best practice when dealing with overloaded servers or hitting rate limits. These issues typically manifest as HTTP status codes like 429 (Too Many Requests), 500 (Internal Server Error), or 503 (Service Unavailable).

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Why Use Retries

  • Handle rate limits gracefully - Automatically retry when you hit provider rate limits
  • Overcome temporary failures - Recover from transient network issues or server overload
  • Improve reliability - Increase the success rate of your LLM requests without manual intervention
If you’re using the AI Gateway, automatic failover is usually better than retries. However, retries are ideal when you must use a specific provider endpoint (e.g., EU-hosted models for compliance, fine-tuned models, or region-specific deployments).

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How It Works

Helicone uses exponential backoff to intelligently space out retry attempts. This strategy:
  • Starts with a short delay (default 1 second)
  • Doubles the wait time after each failed attempt
  • Caps the maximum wait time (default 10 seconds)
  • Prevents overwhelming the server while maximizing success chances
Example: With default settings, retries happen at: 1s → 2s → 4s → 8s → 10s

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Quick Start

To enable automatic retries, add the Helicone-Retry-Enabled: true header to your requests: 
import { OpenAI } from "openai";

const client = new OpenAI({
  baseURL: "https://ai-gateway.helicone.ai",
  apiKey: process.env.HELICONE_API_KEY,
});

const response = await client.chat.completions.create(
  {
    model: "gpt-4o-mini",
    messages: [{ role: "user", content: "How do I enable retries?" }]
  },
  {
    headers: {
      "Helicone-Retry-Enabled": "true", // Add this header and set to true
    }
  }
);
Each retry attempt is logged separately in Helicone, allowing you to track retry patterns and success rates.

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Configuration

Customize retry behavior with these optional headers:
​
Helicone-Retry-Num
string
default:"5"
Maximum number of retry attempts. Set to “0” to disable retries for specific requests.Example: "5" for up to 5 retries
​
Helicone-Retry-Factor
string
default:"2"
Exponential backoff multiplier. Controls how quickly the delay increases between retries.Example: "2" doubles the wait time after each attempt
​
Helicone-Retry-Min-Timeout
string
default:"1000"
Minimum delay between retries in milliseconds.Example: "1000" for 1 second minimum wait
​
Helicone-Retry-Max-Timeout
string
default:"10000"
Maximum delay between retries in milliseconds, regardless of exponential growth.Example: "10000" caps wait time at 10 seconds
All header values must be strings. Numbers should be quoted: "Helicone-Retry-Num": "3" not "Helicone-Retry-Num": 3

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Common Use Cases

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EU-Hosted Model for GDPR Compliance

// Must use Azure OpenAI in Europe - cannot failover to US providers
const client = new OpenAI({
  baseURL: "https://ai-gateway.helicone.ai",
  apiKey: process.env.HELICONE_API_KEY,
});

const response = await client.chat.completions.create(
  {
    // Specify exact Azure deployment - no fallback
    model: "gpt-4o/azure/eu-frankfurt-deployment",  
    messages: [{ role: "user", content: "Process EU customer data" }]
  },
  {
    headers: {
      "Helicone-Retry-Enabled": "true",
      "Helicone-Retry-Num": "5",
      "Helicone-Retry-Min-Timeout": "2000",
      "Helicone-Retry-Max-Timeout": "10000"
    }
  }
);

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Fine-Tuned Model on Specific Provider

# Must use your fine-tuned model - cannot failover to generic models
client = OpenAI(
    base_url="https://ai-gateway.helicone.ai",
    api_key=os.getenv("HELICONE_API_KEY"),
)

response = client.chat.completions.create(
    # Specify provider explicitly for fine-tuned models
    model="ft:gpt-3.5-turbo-0125:your-org::abc123/openai",  
    messages=[{"role": "user", "content": "Domain-specific query"}],
    extra_headers={
      "Helicone-Retry-Enabled": "true",
      "Helicone-Retry-Num": "3",
      "Helicone-Retry-Factor": "2",
    }
)

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Custom Provider Endpoint

// Using a self-hosted or specialized endpoint
const client = new OpenAI({
  baseURL: "https://gateway.helicone.ai/v1",
  apiKey: process.env.HELICONE_API_KEY,
});

const response = await client.chat.completions.create(
  {
    model: "llama-3",
    messages: [{ role: "user", content: "Query for on-premise model" }]
  },
  {
    headers: {
      "Helicone-Target-URL": "https://your-private-llm.company.com",
      "Helicone-Retry-Enabled": "true",
      "Helicone-Retry-Num": "3"
    }
  }
);

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Retry Triggers

Helicone automatically retries requests that fail with these status codes:
  • 429 - Rate limit exceeded
  • 500 - Internal server error
  • 502 - Bad gateway
  • 503 - Service unavailable
  • 504 - Gateway timeout
Requests that fail with client errors (4xx except 429) are not retried, as these typically indicate issues with the request itself.