HTTP 303 See Other vs 429 Too Many Requests
HTTP 303 (See Other) is a 3xx Redirection response, while 429 (Too Many Requests) is a 4xx Client Error response. 303 indicates that the server is redirecting to a different resource using GET, typically after a POST operation (Post/Redirect/Get pattern). In contrast, 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 server is redirecting to a different resource using GET, typically after a POST operation (Post/Redirect/Get pattern).
When You See It
After form submissions to prevent resubmission on browser refresh.
How to Fix
Follow the Location header with a GET request. This is intentional — part of the PRG pattern.
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
303 is a 3xx Redirection response, while 429 is a 4xx Client Error response.
HTTP 303: The server is redirecting to a different resource using GET, typically after a POST operation (Post/Redirect/Get pattern).
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 303 when after form submissions to prevent resubmission on browser refresh.
You encounter 429 when when hitting API rate limits or making too many requests too quickly.
When to Use Which
For 303 (See Other): Follow the Location header with a GET request. This is intentional — part of the PRG pattern. For 429 (Too Many Requests): Check the Retry-After header. Implement exponential backoff. Consider caching responses.