CORS Checker – Outil en ligne gratuit – ToolBox
CORS checker en ligne gratuit : enter URL, method, headers and body to predict preflight and get common fixes for CORS errors.
CORS checker by ToolBox en ligne gratuit : enter an API URL, HTTP method, request headers and body to predict whether the browser will trigger an OPTIONS preflight request, and get actionable fix suggestions for common CORS failures (missing Access-Control-Allow-Origin, methods/headers mismatch, credentials with wildcard origin, and more). Runs fully in-browser; no data is uploaded.