100 Continue

100

Continue

Example HTTP Response

HTTP Response

HTTP/1.1 100 Continue

Common Causes

Client sent Expect: 100-continue header
Server acknowledging it's ready for the request body
Large file uploads checking if server is ready

Technical Details

What does this mean?

The server is saying 'Keep going, I'm listening!' Like a friend nodding along as you tell a story.

Technical Definition

The server has received the request headers and the client should proceed to send the request body.

RFC Says

"The 100 (Continue) status code indicates that the initial part of a request has been received and has not yet been rejected by the server. The server intends to send a final response after the request has been fully received and acted upon."

Plain English:

100 means 'I've read your headers and they look OK - go ahead and send me the rest of the request body.' It's used with the Expect: 100-continue header to avoid sending large request bodies if the server will reject them anyway.

Common Misinterpretation

Don't confuse this with request completion. 100 is just the server saying 'continue sending' - you'll still get a final response (like 200 or 400) after the full request is processed.

View RFC Documentation

Code Snippets

Ready-to-use code for returning this HTTP status in your application:

Node.js

// Express.js
app.get('/example', (req, res) => {
  res.status(100).json({
    error: 'Continue',
    message: 'Your error message here'
  });
});

// Native HTTP
const http = require('http');

http.createServer((req, res) => {
  res.writeHead(100, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({
    error: 'Continue',
    message: 'Your error message here'
  }));
}).listen(3000);

100 Continue FAQ

What causes a 100 Continue error?

Client sent Expect: 100-continue header. Server acknowledging it's ready for the request body. Large file uploads checking if server is ready.

// Express.js app.get('/example', (req, res) => { res.status(100).json({ error: 'Continue', message: 'Your error message here' }); }); // Native HTTP const http = require('http'); http.createServer((req, res) => { res.writeHead(100, { 'Content-Type': 'application/json' }); res.end(JSON.stringify({ error: 'Continue', message: 'Your error message here' })); }).listen(3000);