Continue

What does HTTP 100 Continue mean?

An interim response that tells the client the initial part of the request was received and it should continue sending the request body. It is typically used with the Expect: 100-continue header to avoid sending a large body the server would reject.

1xx responses are provisional — they tell the client the request was received and the process is continuing. They are rarely seen directly in everyday web development.

When you'll see HTTP 100

• A client sends a large request body with an `Expect: 100-continue` header
• The server confirms it is willing to accept the body before the client uploads it

Example

POST /upload HTTP/1.1
Expect: 100-continue

→ HTTP/1.1 100 Continue

Related 1xx status codes