I'm always amazed by those "you're doing Xyz validation wrong" posts. This is 2021. There should be libs out there that do this perfectly and we should be using

I'm always amazed by those "you're doing Xyz validation wrong" posts. This is 2021. There should be libs out there that do this perfectly and we should be using those. Nobody should be writing this kind of thing from scratch, especially not somebody with "precious developer time at a startup". For fun, sure, why not. But doing this from scratch for production software is nonsense. Parsing email adresses, URLs, IPs, OS path names, even parsing common file formats, stack frames or, god forbid, hacking your own crypto. Don't.