303 - See Other
HTTP 303 See Other means the server directs the client to retrieve another resource, usually with GET.
Last reviewed: March 9, 2026|Editorial standard: source-backed technical guidance
What Does See Other Mean?
The server completed or accepted the original request and is directing the client to fetch result state at another URI using a safe retrieval method.
Common Causes
- -POST completion handler follows PRG pattern and redirects clients to GET confirmation resource endpoint.
- -OAuth callback endpoint uses See Other to force safe retrieval of final authorization result page.
- -Form processing service returns 303 to prevent browser refresh from resubmitting original POST payload.
How to Fix See Other
- 1Validate that the Location target resolves and returns the intended retrieval resource for clients.
- 2Confirm clients follow 303 with GET semantics instead of replaying the original mutation method.
- 3Use Post-Redirect-Get patterns consistently across forms, APIs, and workflow completion routes.
Step-by-Step Diagnosis for See Other
- 1Capture original request method plus
Locationtarget returned with 303. - 2Verify follow-up request uses GET and does not replay mutation body.
- 3Inspect framework/proxy/client redirect handling for accidental method/body carry-over.
- 4Retest with manual redirect handling to assert explicit Post-Redirect-Get correctness.
Post-Redirect-Get Flow Integrity
- -Validate PRG sequence boundaries (example: form POST returns 303 to status URI, not back to mutation endpoint).
- -Confirm mutation side effects happen once before redirect (example: duplicate resource creation due accidental mutation replay).
Client Redirect Method Conversion Checks
- -Audit SDK/browser method switching semantics (example: client library incorrectly preserves POST after 303).
- -Verify
LocationURI stability and accessibility (example: relative Location broken behind reverse proxy path rewrite).
Implementation Examples
curl -i -X POST https://api.example.com/v1/orders -H "Content-Type: application/json" -d "{"item":"book"}"
# Response:
# HTTP/1.1 303 See Other
# Location: https://api.example.com/v1/orders/123/statusconst response = await fetch('https://api.example.com/v1/orders', {
method: 'POST',
headers: { 'Accept': 'application/json', 'Content-Type': 'application/json' },
body: JSON.stringify({ item: 'book' }),
redirect: 'manual'
});
if (response.status === 303) {
console.error('Handle 303 See Other:', response.headers.get('location'));
}import requests
response = requests.post(
'https://api.example.com/v1/orders',
headers={'Accept': 'application/json', 'Content-Type': 'application/json'},
json={'item': 'book'},
allow_redirects=False
)
if response.status_code == 303:
print('Handle 303 See Other', response.headers.get('Location'))How to Verify the Fix
- -Execute the original mutation and confirm the client follows to the expected GET resource successfully.
- -Validate no unintended mutation replay occurs during redirect handling in SDK and browser clients.
- -Check observability data to confirm 303 flows complete without looped or broken follow-up requests.
How to Prevent Recurrence
- -Document Post-Redirect-Get patterns and enforce them in shared web and API client libraries.
- -Add integration tests that assert method conversion behavior for 303 across all supported clients.
- -Version redirect behavior changes and verify Location target stability during route migrations.
Pro Tip
- -supply idempotency keys on mutation endpoints even with PRG, so accidental client replay cannot duplicate side effects.
Decision Support
Compare Guide
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Playbook
Resource State Playbook (404 / 410 / ResourceNotFound)
Use this playbook to separate temporary missing-resource lookups from permanent removals, then fix scope, lifecycle, and identifier drift safely.
Official References
Provider Context
This guidance is specific to HTTP services. Always validate implementation details against official provider documentation before deploying to production.