103 Early Hints

An informational HTTP status code that allows the server to send preliminary Link response headers before the final response is ready, enabling browsers to preload critical resources while the server finishes generating the response. For example, a server can send 103 with Link: </app.css>; rel=preload headers as soon as the request is received, then follow with the full 200 response. This can shave hundreds of milliseconds from perceived page load time on uncached dynamic pages.