Бесплатный онлайн-инструмент CORS Checker – ToolBox
Бесплатный онлайн-CORS checker: enter URL, method, headers and body to predict preflight and get common fixes for CORS errors.
Бесплатный онлайн-CORS checker by ToolBox: 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.