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The OpenAlex API uses standard HTTP status codes to indicate success or failure.

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HTTP Status Codes

CodeMeaningWhat to Do
200SuccessRequest completed successfully
301Moved PermanentlyEntity was merged; follow the redirect
400Bad RequestCheck your filter syntax or parameters
403ForbiddenRate limit exceeded; slow down
404Not FoundEntity doesn’t exist
429Too Many RequestsDaily limit exceeded
500Server ErrorTemporary issue; retry with backoff

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Error Response Format

Error responses include a message explaining what went wrong: 
{
  "error": "Invalid filter",
  "message": "Unknown filter field: author_name. Did you mean: authorships.author.id?"
}

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Common Errors

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Invalid Filter Syntax

400 Bad Request
"Invalid filter: publication_year:abc"
Fix: Ensure values match expected types. publication_year expects an integer.

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Unknown Filter Field

400 Bad Request
"Unknown filter field: author_name"
Fix: Use the correct filter field. For authors, use authorships.author.id with an ID, not a name. See Resolve IDs.

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Rate Limit Exceeded

429 Too Many Requests
"Rate limit exceeded"
Fix:
  • Check rate limit headers to see your remaining allowance
  • Add delays between requests
  • Use per_page=100 to reduce total requests
  • Consider a paid plan for higher limits

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Entity Not Found

404 Not Found
"Work W9999999999 not found"
Fix: Verify the ID exists. The entity may have been merged—check if you’re being redirected.

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Retry Logic

Implement exponential backoff for transient errors: 
import time
import requests

def fetch_with_retry(url, max_retries=5):
    for attempt in range(max_retries):
        try:
            response = requests.get(url, timeout=30)

            if response.status_code == 200:
                return response.json()

            if response.status_code == 429:
                # Rate limited - wait longer
                wait_time = 2 ** attempt
                time.sleep(wait_time)
                continue

            if response.status_code >= 500:
                # Server error - retry
                wait_time = 2 ** attempt
                time.sleep(wait_time)
                continue

            # Client error - don't retry
            response.raise_for_status()

        except requests.exceptions.Timeout:
            if attempt < max_retries - 1:
                time.sleep(2 ** attempt)
            else:
                raise

    raise Exception(f"Failed after {max_retries} retries")

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Rate Limit Headers

Every response includes headers showing your current status: 
X-RateLimit-Limit: 10000
X-RateLimit-Remaining: 8766
X-RateLimit-Credits-Used: 1
X-RateLimit-Reset: 43200
Use these to:
  • Monitor your usage
  • Pause before hitting limits
  • Calculate when limits reset (seconds until midnight UTC)

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Best Practices

  1. Always set timeouts — Use 30-second timeouts to avoid hanging requests
  2. Implement backoff — Don’t retry immediately; wait 1s, 2s, 4s, etc.
  3. Check headers — Monitor X-RateLimit-Remaining to avoid hitting limits
  4. Log errors — Record failures for debugging
  5. Use bulk endpoints — Batch requests to reduce total API calls