Best-fit scenarios
- Technical workflows that require rapid iteration
- Cases where you need processing without sending data to external services
- Repeatable operations that can be standardized across teams
HTTP Status Code Database
Search HTTP status codes in one view; instantly review common causes and quick fixes for 4xx/5xx issues during debugging and API support work across releases.
HTTP Status Code Database
This tool runs as a static dictionary. All code explanations are listed in-browser with no external API calls.
Records found: 30
100 — Continue
1xxClient can continue sending request body.
Common causes
- Expect: 100-continue handshake
Quick fixes
- Usually informational; no action needed
101 — Switching Protocols
1xxServer is switching protocols (e.g., WebSocket).
Common causes
- Upgrade header negotiation
Quick fixes
- Verify upgrade headers and server support
200 — OK
2xxRequest succeeded.
Common causes
- Normal successful response
Quick fixes
- No action needed
201 — Created
2xxResource successfully created.
Common causes
- POST or PUT create operation
Quick fixes
- Return Location header for new resource when possible
202 — Accepted
2xxRequest accepted for asynchronous processing.
Common causes
- Queued background processing
Quick fixes
- Provide job/status endpoint for tracking
204 — No Content
2xxRequest succeeded with no response body.
Common causes
- Successful delete/update without payload
Quick fixes
- Ensure clients do not expect JSON body
301 — Moved Permanently
3xxResource moved permanently to a new URL.
Common causes
- Permanent URL change
Quick fixes
- Use absolute target URL and preserve canonical mapping
302 — Found
3xxResource temporarily available at another URL.
Common causes
- Temporary redirect rules
Quick fixes
- Use 307/308 when method preservation matters
304 — Not Modified
3xxCached resource is still valid.
Common causes
- ETag or If-Modified-Since validation
Quick fixes
- Verify cache headers and validator consistency
307 — Temporary Redirect
3xxTemporary redirect preserving HTTP method.
Common causes
- Temporary rerouting with method preservation
Quick fixes
- Confirm clients support 307 semantics
308 — Permanent Redirect
3xxPermanent redirect preserving HTTP method.
Common causes
- Permanent rerouting with method preservation
Quick fixes
- Prefer 308 over 301 for strict method preservation
400 — Bad Request
4xxServer cannot process malformed request.
Common causes
- Invalid JSON
- Missing required fields
- Malformed query
Quick fixes
- Validate request schema and payload format
401 — Unauthorized
4xxAuthentication is required or invalid.
Common causes
- Missing token
- Expired token
- Invalid credentials
Quick fixes
- Send valid auth credentials and refresh expired tokens
403 — Forbidden
4xxRequest understood but access denied.
Common causes
- Permission missing
- Policy restrictions
Quick fixes
- Update roles, scopes, or ACL rules
404 — Not Found
4xxTarget resource could not be found.
Common causes
- Invalid endpoint
- Wrong ID
- Deleted resource
Quick fixes
- Check route path, parameters, and environment base URL
405 — Method Not Allowed
4xxHTTP method not supported for endpoint.
Common causes
- Using POST on GET-only route
Quick fixes
- Use allowed method and verify route handler config
408 — Request Timeout
4xxServer timed out waiting for request.
Common causes
- Slow connection
- Client stalled upload
Quick fixes
- Retry request and optimize payload size
409 — Conflict
4xxRequest conflicts with current resource state.
Common causes
- Duplicate unique field
- Concurrent update collisions
Quick fixes
- Resolve conflicting state and retry with latest data
410 — Gone
4xxResource is permanently removed.
Common causes
- Deprecated endpoint/resource removed
Quick fixes
- Migrate clients to replacement endpoint
413 — Payload Too Large
4xxRequest body exceeds allowed size.
Common causes
- File upload too large
- Oversized JSON payload
Quick fixes
- Compress, chunk, or raise server size limits
415 — Unsupported Media Type
4xxContent type is not supported by server.
Common causes
- Missing/incorrect Content-Type header
Quick fixes
- Send a supported media type (e.g., application/json)
422 — Unprocessable Content
4xxRequest is syntactically valid but semantically invalid.
Common causes
- Validation rule failures
- Business rule mismatch
Quick fixes
- Return field-level validation details and fix input values
429 — Too Many Requests
4xxRate limit exceeded.
Common causes
- Burst traffic
- No backoff strategy
Quick fixes
- Apply retry-after handling and exponential backoff
451 — Unavailable For Legal Reasons
4xxResource blocked for legal reasons.
Common causes
- Regional or legal access restrictions
Quick fixes
- Review legal constraints and regional policies
500 — Internal Server Error
5xxUnexpected server-side failure.
Common causes
- Unhandled exception
- Runtime crash
Quick fixes
- Inspect server logs and add structured error handling
501 — Not Implemented
5xxRequested functionality not implemented.
Common causes
- Missing route capability or server feature
Quick fixes
- Implement missing handler or remove unsupported operation
502 — Bad Gateway
5xxGateway received invalid response from upstream.
Common causes
- Upstream crash
- Proxy configuration mismatch
Quick fixes
- Check upstream health and reverse-proxy config
503 — Service Unavailable
5xxServer temporarily unavailable.
Common causes
- Maintenance window
- Resource exhaustion
Quick fixes
- Scale resources and use retry with backoff
504 — Gateway Timeout
5xxGateway timed out waiting for upstream.
Common causes
- Slow upstream
- Network latency spikes
Quick fixes
- Tune timeouts and optimize upstream latency
505 — HTTP Version Not Supported
5xxServer does not support request HTTP version.
Common causes
- Protocol mismatch
Quick fixes
- Use supported HTTP version and proxy settings
What is this tool?
This tool is a search-enabled static reference database for quickly interpreting HTTP status codes.
The tool is designed to simplify technical workflows for end users. It follows an offline, privacy-first, in-browser flow without server-side uploads.
How to use
- Enter code or keyword in search.
- Optionally select a 1xx–5xx category filter.
- Use common causes and quick fixes to troubleshoot.
Privacy promise
The tool serves static content only. Your searches stay in-browser and are not sent to external services.
This approach is especially useful for users who need low-latency processing and tighter data control.
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Use cases and comparison
This section helps you quickly decide when to use this tool and how it differs from nearby alternatives.
How it differs
Advanced URL Parser: A good first step for validating URL structure in failing endpoint calls.
Offline OpenAPI Workbench: Useful for mapping expected success/error codes after generating API drafts.