HTTP
100 Continue
The server has received the request headers and the client should proceed to send the request body. This lets the client know it can continue with the request or abort if the headers were rejected.
When You See This Code
When a client sends an Expect: 100-continue header, the server responds with 100 before the client sends the body.
How to Fix
This is an interim response — no fix needed. The client should continue sending the request body.
Specification
View RFC / Specification →Guides
Understanding HTTP Status Codes: A Complete Guide
HTTP Fundamentals
HTTP Redirects: 301 vs 302 vs 307 vs 308
HTTP Fundamentals
HTTP Caching: Cache-Control, ETags, and 304 Responses
HTTP Fundamentals
Choosing the Right HTTP Status Codes for REST APIs
API Design
gRPC Status Codes: A Practical Guide
API Design
Debugging 502 Bad Gateway Errors
Debugging & Troubleshooting
Debugging CORS Errors: A Developer's Guide
Debugging & Troubleshooting
Debugging Timeout Errors: 408 and 504
Debugging & Troubleshooting
401 Unauthorized vs 403 Forbidden: When to Use Each
Security & Authentication
Essential HTTP Security Headers
Security & Authentication
Complete Guide to HTTP Methods: GET, POST, PUT, PATCH, DELETE
HTTP Fundamentals
Essential HTTP Headers Every Developer Should Know
HTTP Fundamentals
HTTP/2 vs HTTP/3: What Changed and Why
HTTP Fundamentals
How to Implement and Handle Rate Limiting (429)
API Design
API Versioning Strategies: URL, Header, and Query Param
API Design
Designing Consistent API Error Responses
API Design
Debugging 503 Service Unavailable Errors in Production
Debugging & Troubleshooting
TLS/SSL Certificate Troubleshooting Guide
Debugging & Troubleshooting
OAuth 2.0 Flows Explained: Authorization Code, Client Credentials, PKCE
Security & Authentication
JSON Web Tokens: Structure, Signing, and Common Pitfalls
Security & Authentication
API Keys vs OAuth vs JWT: Choosing the Right Auth Method
Security & Authentication