← All Status Codes
100
Continue
ℹ️ Informational
Info Risk
📖 What Is HTTP 100?
The server has received the request headers and the client should proceed to send the request body. Used in large uploads where the client sends an Expect: 100-continue header.
🛡️ Security Implications
Minimal security risk. Can be abused in slowloris-style attacks by never sending the body after receiving 100 Continue.
🔍 Common Causes
Client sends Expect: 100-continue header before a large POST/PUT body. Server acknowledges it is ready to receive the data.
🔧 How to Fix
No fix needed — this is normal behavior. If causing issues with proxies, the client can omit the Expect header.
🖥️ How to Check
curl -I -o /dev/null -w "%{http_code}" https://example.com