Status Code
A three-digit numeric code in an HTTP response that indicates the outcome of a request. Status codes are grouped into five classes: 1xx (Informational), 2xx (Successful), 3xx (Redirection), 4xx (Client Error), and 5xx (Server Error). Other protocols like SIP, FTP, and SMTP use similar numeric code systems with their own semantics.
Related Protocols
Mentioned in Guides
Understanding HTTP Status Codes: A Complete Guide
HTTP Fundamentals
HTTP Conditional Requests: If-Match, If-None-Match, and Beyond
HTTP Fundamentals
HTTP 103 Early Hints: Preloading Before the Response
HTTP Fundamentals
gRPC Status Codes: A Practical Guide
API Design & Best Practices
Designing Consistent API Error Responses
API Design & Best Practices
Implementing Webhooks: A Complete Guide
API Design & Best Practices
Designing Bulk API Endpoints: Batch Requests and Partial Failures
API Design & Best Practices
Debugging WebSocket Disconnections
Debugging & Troubleshooting
Debugging gRPC Errors and Status Codes
Debugging & Troubleshooting
Diagnosing Email Bounces: Soft (4xx) vs Hard (5xx)
Email Delivery
WebSocket Close Codes: Why Your Connection Dropped
Real-Time Protocols
Designing Error Responses with Problem Details (RFC 9457)
Error Handling Patterns
Status Code Handling in Django
Framework Cookbooks
FastAPI Response Models and Status Codes
Framework Cookbooks
Go HTTP Error Handling Patterns
Framework Cookbooks
gRPC Error Handling Best Practices
Framework Cookbooks
Next.js API Routes: Status Codes, Error Handling, and Middleware
Framework Cookbooks
Flask Error Handling: Custom Pages, API Errors, and Blueprints
Framework Cookbooks
Laravel Exception Handling: Renderable Exceptions and API Resources
Framework Cookbooks
Rust Actix-web Error Handling: ResponseError Trait and Custom Errors
Framework Cookbooks
HTTP/2 Server Push: Promise and Pitfalls
Performance & Optimization
RFC 9110: HTTP Semantics Deep Dive
Protocol Deep Dives
RFC 6455: WebSocket Protocol Deep Dive
Protocol Deep Dives
RFC 5321: SMTP Protocol Deep Dive
Protocol Deep Dives
RFC 7540: HTTP/2 Protocol Deep Dive
Protocol Deep Dives
API Migration: Monolith to Microservices
Migration & Upgrades
Load Balancer Health Checks: HTTP, TCP, and gRPC Probes
Production Infrastructure
Observability for HTTP Status Codes: Metrics, Logs, and Alerts
Production Infrastructure
HTTP Access Log Management: Rotation, Parsing, and Analysis
Production Infrastructure
API Testing Strategies: Unit, Integration, Contract, and E2E
Testing & Mocking
Mock Servers for API Development: WireMock, Prism, and Custom Mocks
Testing & Mocking
API Schema Validation Testing: OpenAPI, JSON Schema, and Schemathesis
Testing & Mocking
Testing Error Scenarios: Simulating 4xx and 5xx Responses
Testing & Mocking
API Performance Benchmarking: Establishing and Tracking Baselines
Testing & Mocking
Defined In
Decision Guides
See Also
Reason Phrase
HTTP Concepts
Response Header
HTTP Concepts
Redirect
HTTP Concepts
REST (Representational State Transfer)
HTTP Concepts
Response Body
API Design
Authentication
Security
Timeout
Networking
Load Balancer
Networking
Reverse Proxy
Networking
Cache-Control
Caching & Performance
ETag (Entity Tag)
Caching & Performance
Problem Details (RFC 9457)
Error Handling
Error Code Mapping
Error Handling
Request-Response Model
Protocol Design
RFC (Request for Comments)
Protocol Design
IANA (Internet Assigned Numbers Authority)
Protocol Design
Protocol Upgrade
Protocol Design
SMTP Relay
Email & SMTP
SMTP Enhanced Status Codes
Email & SMTP
WebSocket Frame
Real-Time & Streaming
SIP Dialog
Real-Time & Streaming
WebSocket Close Code
Real-Time & Streaming
Early Hints (103)
Web Standards
Proxy Authentication
Web Standards
gRPC Status Code
gRPC & RPC
SIP Response Classes
SIP & VoIP
FTP Reply Code
FTP & File Transfer