Access-Control-Allow-Origin: * Access-Control-Allow-Methods: POST, PUT, DELETE Access-Control-Allow-Headers: Content-Type If the preflight fails, the actual request is never sent. | Request Type | Chrome’s Behavior | |--------------|------------------| | Same-origin | Allowed without CORS headers | | Cross-origin, simple | Allowed if server returns Access-Control-Allow-Origin matching the origin or * | | Cross-origin, with credentials (cookies) | Access-Control-Allow-Origin cannot be * ; must be explicit; Access-Control-Allow-Credentials: true required | | Cross-origin, custom header | Preflight OPTIONS request sent | 5. Solving CORS Errors in Chrome For Development Only Option 1: Disable CORS in Chrome (unsafe, only for testing) Windows: chrome.exe --disable-web-security --user-data-dir="C:\temp\chrome-dev"
Header set Access-Control-Allow-Origin "https://yourfrontend.com" a) Private Network Access (CORS-RFC1918) Chrome requires CORS for requests from public sites to localhost/private IPs. cors chrome
app.use((req, res, next) => res.header('Access-Control-Allow-Origin', 'https://yourfrontend.com'); res.header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE'); res.header('Access-Control-Allow-Headers', 'Content-Type'); if (req.method === 'OPTIONS') return res.sendStatus(200); next(); ); if (req.method === 'OPTIONS') return res.sendStatus(200)
add_header 'Access-Control-Allow-Origin' 'https://yourfrontend.com'; add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS'; add_header 'Access-Control-Allow-Methods' 'GET
open -n -a /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --args --user-data-dir="/tmp/chrome_dev_test" --disable-web-security
Request from public site to 192.168.1.100 blocked: Private Network Access Target server must send:
The server must respond with: