anywhere worth working for won't care about a certificate. you'll have to be knowledgeable enough about coding to sound competent in an interview. and that just takes experience.

there's an unlimited amount of training/practice material online to learn the basics.

but just to be realistic about it, if you're looking to be a legit full-time web developer, it's probably gonna take you months of dedicated practice to even get to a intro/intern-level dev gig.