HTTP 401 Unauthorized vs 429 Too Many Requests
Both HTTP 401 (Unauthorized) and 429 (Too Many Requests) belong to the 4xx Client Error category. 401 indicates that the request requires user authentication. The response includes a WWW-Authenticate header indicating the authentication scheme. Meanwhile, 429 means that the user has sent too many requests in a given time (rate limiting). The response should include a Retry-After header.
Description
The request requires user authentication. The response includes a WWW-Authenticate header indicating the authentication scheme.
When You See It
When accessing a protected resource without credentials or with expired tokens.
How to Fix
Include valid authentication credentials (API key, Bearer token, Basic auth) in the Authorization header.
Description
The user has sent too many requests in a given time (rate limiting). The response should include a Retry-After header.
When You See It
When hitting API rate limits or making too many requests too quickly.
How to Fix
Check the Retry-After header. Implement exponential backoff. Consider caching responses.
Key Differences
HTTP 401: The request requires user authentication. The response includes a WWW-Authenticate header indicating the authentication scheme.
HTTP 429: The user has sent too many requests in a given time (rate limiting). The response should include a Retry-After header.
You encounter 401 when when accessing a protected resource without credentials or with expired tokens.
You encounter 429 when when hitting API rate limits or making too many requests too quickly.
When to Use Which
For 401 (Unauthorized): Include valid authentication credentials (API key, Bearer token, Basic auth) in the Authorization header. For 429 (Too Many Requests): Check the Retry-After header. Implement exponential backoff. Consider caching responses.